View Compilation Error

0_0_1416569_31616.cpp: In function `void FD(int)':
0_0_1416569_31616.cpp:15: error: `M_PI' undeclared (first use this function)
0_0_1416569_31616.cpp:15: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_1416569_31616.cpp: In function `int myatoi(char*, int)':
0_0_1416569_31616.cpp:32: error: `atoi' undeclared (first use this function)
0_0_1416569_31616.cpp: In function `int main()':
0_0_1416569_31616.cpp:62: error: `atoi' undeclared (first use this function)