View Compilation Error

355939_0_26555.cpp: In function `int main()':
355939_0_26555.cpp:23: error: `abs' undeclared (first use this function)
355939_0_26555.cpp:23: error: (Each undeclared identifier is reported only once for each function it appears in.)
355939_0_26555.cpp:45: error: `rerutn' undeclared (first use this function)
355939_0_26555.cpp:45: error: expected `;' before numeric constant