#include <stdio.h>
#include <math.h>
void main()
{
int s;
float n,t,pi;
t=1,pi=0;n=1.0;s=1;
while(fabs(t)>1e-6)
{
 pi=pi+t;
 n=n+2;
 s=-s;
 t=s/n;
}
pi=pi*4;
printf("pi=%10.6f/n",pi);
}