View Compilation Error

36571_0_2755.cpp:4: error: `main' must return `int'
36571_0_2755.cpp: In function `int main(...)':
36571_0_2755.cpp:33: error: `abs' undeclared (first use this function)
36571_0_2755.cpp:33: error: (Each undeclared identifier is reported only once for each function it appears in.)