diff --git a/include/boost/algorithm/string/detail/finder.hpp b/include/boost/algorithm/string/detail/finder.hpp
index 2162264..4dc2fe7 100644
--- a/include/boost/algorithm/string/detail/finder.hpp
+++ b/include/boost/algorithm/string/detail/finder.hpp
@@ -90,7 +90,7 @@ namespace boost {
 
 //  find last functor -----------------------------------------------//
 
-            // find the last match a subsequnce in the sequence ( functor )
+            // find the last match a subseqeunce in the sequence ( functor )
             /*
                 Returns a pair <begin,end> marking the subsequence in the sequence.
                 If the find fails, returns <End,End>
@@ -200,7 +200,7 @@ namespace boost {
 
 //  find n-th functor -----------------------------------------------//
 
-            // find the n-th match of a subsequnce in the sequence ( functor )
+            // find the n-th match of a subsequence in the sequence ( functor )
             /*
                 Returns a pair <begin,end> marking the subsequence in the sequence.
                 If the find fails, returns <End,End>
@@ -212,12 +212,15 @@ namespace boost {
                 typedef first_finderF<
                     search_iterator_type,
                     PredicateT> first_finder_type;
+				typedef last_finderF<
+					search_iterator_type,
+					PredicateT> last_finder_type;
 
                 // Construction
                 template< typename SearchT >
                 nth_finderF(
                         const SearchT& Search,
-                        unsigned int Nth,
+                        int Nth,
                         PredicateT Comp) :
                     m_Search(begin(Search), end(Search)),
                     m_Nth(Nth),
@@ -225,7 +228,7 @@ namespace boost {
                 nth_finderF(
                         search_iterator_type SearchBegin,
                         search_iterator_type SearchEnd,
-                        unsigned int Nth,
+                        int Nth,
                         PredicateT Comp) :
                     m_Search(SearchBegin, SearchEnd),
                     m_Nth(Nth),
@@ -237,6 +240,26 @@ namespace boost {
                 operator()(
                     ForwardIteratorT Begin,
                     ForwardIteratorT End ) const
+                {
+					if(m_Nth>=0)
+					{
+						return find_forward(Begin, End, m_Nth);
+					}
+					else
+					{
+						return find_backward(Begin, End, -m_Nth);
+					}
+
+                }
+
+			private:
+				// Implementation helpers
+                template< typename ForwardIteratorT >
+                iterator_range<ForwardIteratorT>
+                find_forward(
+                    ForwardIteratorT Begin,
+                    ForwardIteratorT End,
+					unsigned int N) const
                 {
                     typedef ForwardIteratorT input_iterator_type;
                     typedef iterator_range<ForwardIteratorT> result_type;
@@ -245,13 +268,13 @@ namespace boost {
                     if( boost::empty(m_Search) )
                         return result_type( End, End );
 
-                    // Instantiate find funtor
+                    // Instantiate find functor
                     first_finder_type first_finder(
                         m_Search.begin(), m_Search.end(), m_Comp );
 
                     result_type M( Begin, Begin );
 
-                    for( unsigned int n=0; n<=m_Nth; ++n )
+                    for( unsigned int n=0; n<=N; ++n )
                     {
                         // find next match
                         M=first_finder( end(M), End );
@@ -266,14 +289,101 @@ namespace boost {
                     return M;
                 }
 
+                template< typename ForwardIteratorT >
+                iterator_range<ForwardIteratorT>
+                find_backward(
+                    ForwardIteratorT Begin,
+                    ForwardIteratorT End,
+					unsigned int N) const
+                {
+                    typedef ForwardIteratorT input_iterator_type;
+                    typedef iterator_range<ForwardIteratorT> result_type;
+
+                    // Sanity check
+                    if( boost::empty(m_Search) )
+                        return result_type( End, End );
+
+                    // Instantiate find functor
+                    last_finder_type last_finder(
+                        m_Search.begin(), m_Search.end(), m_Comp );
+
+                    result_type M( End, End );
+
+                    for( unsigned int n=1; n<=N; ++n )
+                    {
+                        // find next match
+                        M=last_finder( Begin, begin(M) );
+
+                        if ( !M )
+                        {
+                            // Subsequence not found, return
+                            return M;
+                        }
+                    }
+
+                    return M;
+                }
+
+
             private:
                 iterator_range<search_iterator_type> m_Search;
-                unsigned int m_Nth;
+                int m_Nth;
                 PredicateT m_Comp;
             };
 
 //  find head functor -----------------------------------------------//
 
+			// Find head implementation
+			template<typename ForwardIteratorT>
+				iterator_range<ForwardIteratorT>
+			find_head_impl(
+				ForwardIteratorT Begin,
+				ForwardIteratorT End,
+				unsigned int N )
+			{
+				typedef BOOST_STRING_TYPENAME boost::detail::
+					iterator_traits<ForwardIteratorT>::iterator_category category;
+
+				return find_head_impl( Begin, End, N, category() );
+			}
+
+			template<typename ForwardIteratorT>
+				iterator_range<ForwardIteratorT>
+			find_head_impl(
+				ForwardIteratorT Begin,
+				ForwardIteratorT End,
+				unsigned int N,
+				std::forward_iterator_tag )
+			{
+				typedef ForwardIteratorT input_iterator_type;
+				typedef iterator_range<ForwardIteratorT> result_type;
+
+				input_iterator_type It=Begin;
+				for(
+					unsigned int Index=0;
+					Index<N && It!=End; ++Index,++It ) {};
+
+				return result_type( Begin, It );
+			}
+
+			template< typename ForwardIteratorT >
+				iterator_range<ForwardIteratorT>
+			find_head_impl(
+				ForwardIteratorT Begin,
+				ForwardIteratorT End,
+				unsigned int N,
+				std::random_access_iterator_tag )
+			{
+				typedef ForwardIteratorT input_iterator_type;
+				typedef iterator_range<ForwardIteratorT> result_type;
+
+				if ( (End<=Begin) || ( static_cast<unsigned int>(End-Begin) < N ) )
+					return result_type( Begin, End );
+
+				return result_type(Begin,Begin+N);
+			}
+
+
             // find a head in the sequence ( functor )
             /*
                 This functor find a head of the specified range. For
@@ -283,7 +393,7 @@ namespace boost {
             struct head_finderF
             {
                 // Construction
-                head_finderF( unsigned int N ) : m_N(N) {}
+                head_finderF( int N ) : m_N(N) {}
 
                 // Operation
                 template< typename ForwardIteratorT >
@@ -292,54 +402,99 @@ namespace boost {
                     ForwardIteratorT Begin,
                     ForwardIteratorT End ) const
                 {
-                    typedef BOOST_STRING_TYPENAME boost::detail::
-                        iterator_traits<ForwardIteratorT>::iterator_category category;
+					if(m_N>=0)
+					{
+						return find_head_impl( Begin, End, m_N );
+					}
+					else
+					{
+						iterator_range<ForwardIteratorT> Res=
+							find_tail_impl( Begin, End, -m_N );
 
-                    return findit( Begin, End, category() );
+						return make_iterator_range(Begin, Res.begin());
+					}
                 }
 
             private:
-                // Find operation implementation
-                template< typename ForwardIteratorT >
-                    iterator_range<ForwardIteratorT>
-                findit(
-                    ForwardIteratorT Begin,
-                    ForwardIteratorT End,
-                    std::forward_iterator_tag ) const
-                {
-                    typedef ForwardIteratorT input_iterator_type;
-                    typedef iterator_range<ForwardIteratorT> result_type;
-
-                    input_iterator_type It=Begin;
-                    for(
-                        unsigned int Index=0;
-                        Index<m_N && It!=End; ++Index,++It ) {};
-
-                    return result_type( Begin, It );
-                }
-
-                template< typename ForwardIteratorT >
-                    iterator_range<ForwardIteratorT>
-                findit(
-                    ForwardIteratorT Begin,
-                    ForwardIteratorT End,
-                    std::random_access_iterator_tag ) const
-                {
-                    typedef ForwardIteratorT input_iterator_type;
-                    typedef iterator_range<ForwardIteratorT> result_type;
-
-                    if ( (End<=Begin) || ( static_cast<unsigned int>(End-Begin) < m_N ) )
-                        return result_type( Begin, End );
-
-                    return result_type(Begin,Begin+m_N);
-                }
-
-            private:
-                unsigned int m_N;
+                int m_N;
             };
 
 //  find tail functor -----------------------------------------------//
 
+            // Operation
+            template< typename ForwardIteratorT >
+            iterator_range<ForwardIteratorT>
+            find_tail_impl(
+                ForwardIteratorT Begin,
+                ForwardIteratorT End,
+				unsigned int N )
+            {
+                typedef BOOST_STRING_TYPENAME boost::detail::
+                    iterator_traits<ForwardIteratorT>::iterator_category category;
+
+                return find_tail_impl( Begin, End, N, category() );
+            }
+
+            template< typename ForwardIteratorT >
+                iterator_range<ForwardIteratorT>
+            find_tail_impl(
+                ForwardIteratorT Begin,
+                ForwardIteratorT End,
+				unsigned int N,
+                std::forward_iterator_tag )
+            {
+                typedef ForwardIteratorT input_iterator_type;
+                typedef iterator_range<ForwardIteratorT> result_type;
+
+                unsigned int Index=0;
+                input_iterator_type It=Begin;
+                input_iterator_type It2=Begin;
+
+                // Advance It2 by N increments
+                for( Index=0; Index<N && It2!=End; ++Index,++It2 ) {};
+
+                // Advance It, It2 to the end
+                for(; It2!=End; ++It,++It2 ) {};
+
+                return result_type( It, It2 );
+            }
+
+            template< typename ForwardIteratorT >
+                iterator_range<ForwardIteratorT>
+            find_tail_impl(
+                ForwardIteratorT Begin,
+                ForwardIteratorT End,
+				unsigned int N,
+                std::bidirectional_iterator_tag )
+            {
+                typedef ForwardIteratorT input_iterator_type;
+                typedef iterator_range<ForwardIteratorT> result_type;
+
+                input_iterator_type It=End;
+                for(
+                    unsigned int Index=0;
+                    Index<N && It!=Begin; ++Index,--It ) {};
+
+                return result_type( It, End );
+            }
+
+            template< typename ForwardIteratorT >
+                iterator_range<ForwardIteratorT>
+            find_tail_impl(
+                ForwardIteratorT Begin,
+                ForwardIteratorT End,
+				unsigned int N,
+                std::random_access_iterator_tag )
+            {
+                typedef ForwardIteratorT input_iterator_type;
+                typedef iterator_range<ForwardIteratorT> result_type;
+
+                if ( (End<=Begin) || ( static_cast<unsigned int>(End-Begin) < N ) )
+                    return result_type( Begin, End );
+
+                return result_type( End-N, End );
+            }
+
             // find a tail in the sequence ( functor )
             /*
                 This functor find a tail of the specified range. For
@@ -349,7 +504,7 @@ namespace boost {
             struct tail_finderF
             {
                 // Construction
-                tail_finderF( unsigned int N ) : m_N(N) {}
+                tail_finderF( int N ) : m_N(N) {}
 
                 // Operation
                 template< typename ForwardIteratorT >
@@ -358,74 +513,21 @@ namespace boost {
                     ForwardIteratorT Begin,
                     ForwardIteratorT End ) const
                 {
-                    typedef BOOST_STRING_TYPENAME boost::detail::
-                        iterator_traits<ForwardIteratorT>::iterator_category category;
+					if(m_N>=0)
+					{
+						return find_tail_impl( Begin, End, m_N );
+					}
+					else
+					{
+						iterator_range<ForwardIteratorT> Res=
+							find_head_impl( Begin, End, -m_N );
 
-                    return findit( Begin, End, category() );
+						return make_iterator_range(Res.end(), End);
+					}
                 }
 
             private:
-                // Find operation implementation
-                template< typename ForwardIteratorT >
-                    iterator_range<ForwardIteratorT>
-                findit(
-                    ForwardIteratorT Begin,
-                    ForwardIteratorT End,
-                    std::forward_iterator_tag ) const
-                {
-                    typedef ForwardIteratorT input_iterator_type;
-                    typedef iterator_range<ForwardIteratorT> result_type;
-
-                    unsigned int Index=0;
-                    input_iterator_type It=Begin;
-                    input_iterator_type It2=Begin;
-
-                    // Advance It2 by N incremets
-                    for( Index=0; Index<m_N && It2!=End; ++Index,++It2 ) {};
-
-                    // Advance It, It2 to the end
-                    for(; It2!=End; ++It,++It2 ) {};
-
-                    return result_type( It, It2 );
-                }
-
-                template< typename ForwardIteratorT >
-                    iterator_range<ForwardIteratorT>
-                findit(
-                    ForwardIteratorT Begin,
-                    ForwardIteratorT End,
-                    std::bidirectional_iterator_tag ) const
-                {
-                    typedef ForwardIteratorT input_iterator_type;
-                    typedef iterator_range<ForwardIteratorT> result_type;
-
-                    input_iterator_type It=End;
-                    for(
-                        unsigned int Index=0;
-                        Index<m_N && It!=Begin; ++Index,--It ) {};
-
-                    return result_type( It, End );
-                }
-
-                template< typename ForwardIteratorT >
-                    iterator_range<ForwardIteratorT>
-                findit(
-                    ForwardIteratorT Begin,
-                    ForwardIteratorT End,
-                    std::random_access_iterator_tag ) const
-                {
-                    typedef ForwardIteratorT input_iterator_type;
-                    typedef iterator_range<ForwardIteratorT> result_type;
-
-                    if ( (End<=Begin) || ( static_cast<unsigned int>(End-Begin) < m_N ) )
-                        return result_type( Begin, End );
-
-                    return result_type( End-m_N, End );
-                }
-
-
-            private:
-                unsigned int m_N;
+                int m_N;
             };
 
 //  find token functor -----------------------------------------------//
@@ -475,7 +577,7 @@ namespace boost {
                         }
                         else
                         {
-                            // Advance by one possition
+                            // Advance by one position
                             ++It2;
                         }
 
diff --git a/include/boost/algorithm/string/erase.hpp b/include/boost/algorithm/string/erase.hpp
index dd499d6..0915e72 100644
--- a/include/boost/algorithm/string/erase.hpp
+++ b/include/boost/algorithm/string/erase.hpp
@@ -400,7 +400,7 @@ namespace boost {
             OutputIteratorT Output,
             const Range1T& Input,
             const Range2T& Search,
-            unsigned int Nth )
+            int Nth )
         {
             return find_format_copy(
                 Output,
@@ -417,7 +417,7 @@ namespace boost {
         inline SequenceT erase_nth_copy( 
             const SequenceT& Input,
             const RangeT& Search,
-            unsigned int Nth )
+            int Nth )
         {
             return find_format_copy( 
                 Input, 
@@ -438,7 +438,7 @@ namespace boost {
         inline void erase_nth( 
             SequenceT& Input,
             const RangeT& Search,
-            unsigned int Nth )
+            int Nth )
         {
             find_format( 
                 Input, 
@@ -473,7 +473,7 @@ namespace boost {
             OutputIteratorT Output,
             const Range1T& Input,
             const Range2T& Search,
-            unsigned int Nth,
+            int Nth,
             const std::locale& Loc=std::locale() )
         {
             return find_format_copy(
@@ -491,7 +491,7 @@ namespace boost {
         inline SequenceT ierase_nth_copy( 
             const SequenceT& Input,
             const RangeT& Search,
-            unsigned int Nth,
+            int Nth,
             const std::locale& Loc=std::locale() )
         {
             return find_format_copy( 
@@ -514,7 +514,7 @@ namespace boost {
         inline void ierase_nth( 
             SequenceT& Input,
             const RangeT& Search,
-            unsigned int Nth,
+            int Nth,
             const std::locale& Loc=std::locale() )
         {
             find_format( 
@@ -687,7 +687,7 @@ namespace boost {
         inline OutputIteratorT erase_head_copy(
             OutputIteratorT Output,
             const RangeT& Input,
-            unsigned int N )
+            int N )
         {
             return find_format_copy(
                 Output,
@@ -703,7 +703,7 @@ namespace boost {
         template<typename SequenceT>
         inline SequenceT erase_head_copy( 
             const SequenceT& Input,
-            unsigned int N )
+            int N )
         {
             return find_format_copy( 
                 Input,
@@ -723,7 +723,7 @@ namespace boost {
         template<typename SequenceT>
         inline void erase_head( 
             SequenceT& Input,
-            unsigned int N )
+            int N )
         {
             find_format( 
                 Input, 
@@ -755,7 +755,7 @@ namespace boost {
         inline OutputIteratorT erase_tail_copy(
             OutputIteratorT Output,
             const RangeT& Input,
-            unsigned int N )
+            int N )
         {
             return find_format_copy(
                 Output,
@@ -771,7 +771,7 @@ namespace boost {
         template<typename SequenceT>
         inline SequenceT erase_tail_copy( 
             const SequenceT& Input,
-            unsigned int N )
+            int N )
         {
             return find_format_copy( 
                 Input,
@@ -791,7 +791,7 @@ namespace boost {
         template<typename SequenceT>
         inline void erase_tail( 
             SequenceT& Input,
-            unsigned int N )
+            int N )
         {
             find_format( 
                 Input, 
diff --git a/include/boost/algorithm/string/find.hpp b/include/boost/algorithm/string/find.hpp
index 8a2d820..b5119ac 100644
--- a/include/boost/algorithm/string/find.hpp
+++ b/include/boost/algorithm/string/find.hpp
@@ -188,7 +188,7 @@ namespace boost {
         find_nth( 
             Range1T& Input, 
             const Range2T& Search,
-            unsigned int Nth)
+            int Nth)
         {
             return nth_finder(Search,Nth)(
                 begin(Input),end(Input));
@@ -218,7 +218,7 @@ namespace boost {
         ifind_nth( 
             Range1T& Input, 
             const Range2T& Search,
-            unsigned int Nth,
+            int Nth,
             const std::locale& Loc=std::locale())
         {
             return nth_finder(Search,Nth,is_iequal(Loc))(
@@ -248,7 +248,7 @@ namespace boost {
             BOOST_STRING_TYPENAME range_result_iterator<RangeT>::type>
         find_head( 
             RangeT& Input, 
-            unsigned int N)
+            int N)
         {
             return head_finder(N)(
                 begin(Input),end(Input));      
@@ -278,7 +278,7 @@ namespace boost {
             BOOST_STRING_TYPENAME range_result_iterator<RangeT>::type>
         find_tail( 
             RangeT& Input, 
-            unsigned int N)
+            int N)
         {
             return tail_finder(N)(
                 begin(Input),end(Input));      
diff --git a/include/boost/algorithm/string/finder.hpp b/include/boost/algorithm/string/finder.hpp
index 8c4962e..8ed21a7 100644
--- a/include/boost/algorithm/string/finder.hpp
+++ b/include/boost/algorithm/string/finder.hpp
@@ -132,7 +132,7 @@ namespace boost {
             is_equal>
         nth_finder( 
             const ContainerT& Search, 
-            unsigned int Nth)
+            int Nth)
         {
             return 
                 detail::nth_finderF<
@@ -150,7 +150,7 @@ namespace boost {
             PredicateT>
         nth_finder( 
             const ContainerT& Search, 
-            unsigned int Nth, 
+            int Nth, 
             PredicateT Comp )
         {
             return 
@@ -172,7 +172,7 @@ namespace boost {
             \return An instance of the \c head_finder object
         */
         inline detail::head_finderF
-        head_finder( unsigned int N )
+        head_finder( int N )
         {
             return detail::head_finderF(N);
         }
@@ -189,7 +189,7 @@ namespace boost {
             \return An instance of the \c tail_finder object
         */
         inline detail::tail_finderF
-        tail_finder( unsigned int N )
+        tail_finder( int N )
         {
             return detail::tail_finderF(N);
         }
diff --git a/include/boost/algorithm/string/replace.hpp b/include/boost/algorithm/string/replace.hpp
index 768aa3d..3a5df1f 100644
--- a/include/boost/algorithm/string/replace.hpp
+++ b/include/boost/algorithm/string/replace.hpp
@@ -443,7 +443,7 @@ namespace boost {
             OutputIteratorT Output,
             const Range1T& Input,
             const Range2T& Search,
-            unsigned int Nth,
+            int Nth,
             const Range3T& Format )
         {
             return find_format_copy(
@@ -461,7 +461,7 @@ namespace boost {
         inline SequenceT replace_nth_copy( 
             const SequenceT& Input,
             const Range1T& Search,
-            unsigned int Nth,
+            int Nth,
             const Range2T& Format )
         {
             return find_format_copy( 
@@ -484,7 +484,7 @@ namespace boost {
         inline void replace_nth( 
             SequenceT& Input,
             const Range1T& Search,
-            unsigned int Nth,
+            int Nth,
             const Range2T& Format )
         {
             find_format( 
@@ -523,7 +523,7 @@ namespace boost {
             OutputIteratorT Output,
             const Range1T& Input,
             const Range2T& Search,
-            unsigned int Nth,
+            int Nth,
             const Range3T& Format,
             const std::locale& Loc=std::locale() )
         {
@@ -542,7 +542,7 @@ namespace boost {
         inline SequenceT ireplace_nth_copy( 
             const SequenceT& Input,
             const Range1T& Search,
-            unsigned int Nth,
+            int Nth,
             const Range2T& Format,
             const std::locale& Loc=std::locale() )
         {
@@ -568,7 +568,7 @@ namespace boost {
         inline void ireplace_nth( 
             SequenceT& Input,
             const Range1T& Search,
-            unsigned int Nth,
+            int Nth,
             const Range2T& Format,
             const std::locale& Loc=std::locale() )
         {
@@ -759,7 +759,7 @@ namespace boost {
         inline OutputIteratorT replace_head_copy(
             OutputIteratorT Output,
             const Range1T& Input,
-            unsigned int N,
+            int N,
             const Range2T& Format )
         {
             return find_format_copy(
@@ -776,7 +776,7 @@ namespace boost {
         template<typename SequenceT, typename RangeT>
         inline SequenceT replace_head_copy( 
             const SequenceT& Input,
-            unsigned int N,
+            int N,
             const RangeT& Format )
         {
             return find_format_copy( 
@@ -799,7 +799,7 @@ namespace boost {
         template<typename SequenceT, typename RangeT>
         inline void replace_head( 
             SequenceT& Input,
-            unsigned int N,
+            int N,
             const RangeT& Format )
         {
             find_format( 
@@ -835,7 +835,7 @@ namespace boost {
         inline OutputIteratorT replace_tail_copy(
             OutputIteratorT Output,
             const Range1T& Input,
-            unsigned int N,
+            int N,
             const Range2T& Format )
         {
             return find_format_copy(
@@ -852,7 +852,7 @@ namespace boost {
         template<typename SequenceT, typename RangeT>
         inline SequenceT replace_tail_copy( 
             const SequenceT& Input,
-            unsigned int N,
+            int N,
             const RangeT& Format )
         {
             return find_format_copy( 
@@ -875,7 +875,7 @@ namespace boost {
         template<typename SequenceT, typename RangeT>
         inline void replace_tail( 
             SequenceT& Input,
-            unsigned int N,
+            int N,
             const RangeT& Format )
         {
             find_format(