View Compilation Error

0_0_27432076_20598.cpp: In function 'int main()':
0_0_27432076_20598.cpp:33:23: error: 'M_PI' was not declared in this scope
         ans=log10(2.0*M_PI)/2.0+(k+0.5)*log10(k)-k*log10(M_E);
                       ^
0_0_27432076_20598.cpp:33:58: error: 'M_E' was not declared in this scope
         ans=log10(2.0*M_PI)/2.0+(k+0.5)*log10(k)-k*log10(M_E);
                                                          ^