View Compilation Error

0_0_23004648_24638.cpp: In function 'int main()':
0_0_23004648_24638.cpp:16:41: error: 'M_PI' was not declared in this scope
  long long l=log10((long double)(sqrt(2*M_PI*n))) +n*log10((long double)n/M_E);
                                         ^
0_0_23004648_24638.cpp:16:75: error: 'M_E' was not declared in this scope
  long long l=log10((long double)(sqrt(2*M_PI*n))) +n*log10((long double)n/M_E);
                                                                           ^