0_0_15009980_19637.cpp: In function 'int main()': 0_0_15009980_19637.cpp:11:47: error: 'M_PI' was not declared in this scope printf("%d\n",(int)((N*log(N)-N+0.5*log(2*N*M_PI))/log(10))+1);//斯特林公式 ^