#include<stdio.h> #include<math.h> int main(void) { int n,denominator=1,flag=1; double item=1.0,pi; scanf("%d",&n); if((n>=3)&&(n<=8)){ while(fabs(item)<pow(10,-n)){ item=flag*1.0/denominator; pi=pi+item; flag=-flag; denominator=denominator+2; } pi=pi*4; printf("%.6f ",pi); } else printf("Error!");
return 0; }