View Compilation Error

0_0_6995837_26814.cpp: In function `int main()':
0_0_6995837_26814.cpp:8: error: `ABS' undeclared (first use this function)
0_0_6995837_26814.cpp:8: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6995837_26814.cpp:8: error: expected `;' before "a"