foo.cpp: In function 'int main(int, char**)':
foo.cpp:13:17: error: reference to 'end' is ambiguous
     cin>>start>>end;
                 ^
foo.cpp:9:14: note: candidates are: std::string end
 string start,end;
              ^
In file included from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\basic_string.h:42:0,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\string:52,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\locale_classes.h:40,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\ios_base.h:41,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\ios:42,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\ostream:38,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\iostream:39,
                 from foo.cpp:1:
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\initializer_list:99:5: note:                 template<class _Tp> constexpr const _Tp* std::end(std::initializer_list<_Tp>)
     end(initializer_list<_Tp> __ils) noexcept
     ^
In file included from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\string:51:0,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\locale_classes.h:40,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\ios_base.h:41,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\ios:42,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\ostream:38,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\iostream:39,
                 from foo.cpp:1:
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\range_access.h:97:5: note:                 template<class _Tp, unsigned int _Nm> _Tp* std::end(_Tp (&)[_Nm])
     end(_Tp (&__arr)[_Nm])
     ^
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\range_access.h:78:5: note:                 template<class _Container> decltype (__cont.end()) std::end(const _Container&)
     end(const _Container& __cont) -> decltype(__cont.end())
     ^
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\range_access.h:68:5: note:                 template<class _Container> decltype (__cont.end()) std::end(_Container&)
     end(_Container& __cont) -> decltype(__cont.end())
     ^
foo.cpp: In function 'int bfs()':
foo.cpp:34:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i!=w1.size();++i)
                          ^
foo.cpp:36:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     while(k<n.size())
                    ^
foo.cpp:40:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(p==string::npos) break;
                 ^
foo.cpp:44:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<w2[i].size();++j)
                            ^
foo.cpp:46:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=p+w1[i].size();j<n.size();++j)
                                     ^
foo.cpp:51:10: error: reference to 'end' is ambiguous
   if(n1==end) return l[n1];
          ^
foo.cpp:9:14: note: candidates are: std::string end
 string start,end;
              ^
In file included from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\basic_string.h:42:0,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\string:52,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\locale_classes.h:40,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\bits\ios_base.h:41,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\ios:42,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\ostream:38,
                 from c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\iostream:39,
                 from foo.cpp:1:
c:\tdm-gcc-32\lib\gcc\mingw32\4.8.1\include\c++\initializer_list:9