View Compilation Error

0_0_30767271_29393.c: In function 'main':
0_0_30767271_29393.c:12:45: error: 'M_PI' undeclared (first use in this function)
         printf("%d\n", 1+(int)(log10(sqrt(2*M_PI*n)) + n*log10(n/M_E)));//Stirling
                                             ^
0_0_30767271_29393.c:12:45: note: each undeclared identifier is reported only once for each function it appears in
0_0_30767271_29393.c:12:66: error: 'M_E' undeclared (first use in this function)
         printf("%d\n", 1+(int)(log10(sqrt(2*M_PI*n)) + n*log10(n/M_E)));//Stirling
                                                                  ^
0_0_30767271_29393.c:12:73: error: expected expression before '/' token
         printf("%d\n", 1+(int)(log10(sqrt(2*M_PI*n)) + n*log10(n/M_E)));//Stirling
                                                                         ^