View Compilation Error

0_0_18923609_21452.c: In function 'main':
0_0_18923609_21452.c:11:35: error: 'M_PI' undeclared (first use in this function)
   printf("%lu\n",(size_t)(log10(2*M_PI*num)/2+num*log10(num/M_E)+1));
                                   ^
0_0_18923609_21452.c:11:35: note: each undeclared identifier is reported only once for each function it appears in
0_0_18923609_21452.c:11:61: error: 'M_E' undeclared (first use in this function)
   printf("%lu\n",(size_t)(log10(2*M_PI*num)/2+num*log10(num/M_E)+1));
                                                             ^