View Compilation Error

0_0_1330949_7591.cpp: In function `bool sccins(double, double, double, int)':
0_0_1330949_7591.cpp:38: error: `abs' undeclared (first use this function)
0_0_1330949_7591.cpp:38: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_1330949_7591.cpp: In function `void solve()':
0_0_1330949_7591.cpp:95: error: `abs' undeclared (first use this function)