View Compilation Error

743951_0_0_32607.cpp: In function `bool DFS(int, int, int)':
743951_0_0_32607.cpp:18: error: `abs' undeclared (first use this function)
743951_0_0_32607.cpp:18: error: (Each undeclared identifier is reported only once for each function it appears in.)
743951_0_0_32607.cpp: In function `int main()':
743951_0_0_32607.cpp:62: error: `abs' undeclared (first use this function)