View Compilation Error

0_0_36576361_32652.cpp: In function 'int main()':
0_0_36576361_32652.cpp:56:29: error: reference to 'rank' is ambiguous
   printf("Case #%d: %d\n",++rank,ans);
                             ^
0_0_36576361_32652.cpp:6:41: note: candidates are: int rank
 int n,m,x[N],y[N],k,af,bf,t,ans,tong[N],rank;
                                         ^
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/move.h:57:0,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/stl_pair.h:59,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/stl_algobase.h:64,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/char_traits.h:39,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/ios:40,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/ostream:38,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/iostream:39,
                 from 0_0_36576361_32652.cpp:2:
GCC4.9.2/x86_64-w64-mingw32/include/c++/type_traits:1340:12: note:                 template<class> struct std::rank
     struct rank
            ^