View Compilation Error

0_0_11020771_16305.cpp: In function `void dfs(int, int, int, int)':
0_0_11020771_16305.cpp:24: error: call of overloaded `abs(int&)' is ambiguous
GCC/bin/../lib/gcc/mingw32/3.4.2/../../../../include/c++/3.4.2/cmath:89: note: candidates are: double std::abs(double)
GCC/bin/../lib/gcc/mingw32/3.4.2/../../../../include/c++/3.4.2/cmath:93: note:                 float std::abs(float)
GCC/bin/../lib/gcc/mingw32/3.4.2/../../../../include/c++/3.4.2/cmath:97: note:                 long double std::abs(long double)