>>553
#include <stdio.h>
#include <stdlib.h>
int main(){
int i,j;
double k,x,y,pi;
scanf("%d",&j);
k=0.0;
for(i=0;i<=j;i++){
x=rand()/(RAND_MAX+1.0);
y=rand()/(RAND_MAX+1.0);
if((x*x+y*y)<1.0)k+=1.0;}
pi=k/j*4.0;
printf("%lf\n",pi);
return 0;}