#include<stdio.h>
#include<math.h>
int main(){
int sign=1;
double pi=0.0,n=1.0,term=1.0;
while(fabs(term)>=1e-6){
pi=pi+term;
n+=2;
sign=-sign;
term=sign/n;
}
pi*=4;
printf("%10.8f",pi);
}
#include<stdio.h>
#include<math.h>
int main(){
int sign=1;
double pi=0.0,n=1.0,term=1.0;
while(fabs(term)>=1e-6){
pi=pi+term;
n+=2;
sign=-sign;
term=sign/n;
}
pi*=4;
printf("%10.8f",pi);
}