View Compilation Error

0_0_8734672_19981.cpp:3:15: math: No such file or directory
0_0_8734672_19981.cpp: In function `void dfs(int, int, int)':
0_0_8734672_19981.cpp:12: error: `abs' undeclared (first use this function)
0_0_8734672_19981.cpp:12: error: (Each undeclared identifier is reported only once for each function it appears in.)