#include <stdio.h>
#include <time.h>
#include <stdlib.h>
main(){int i,n=9<<21;double a,b,c=0,r=RAND_MAX;srand(time(0));for(i=0;i<n;
i++){a=rand();b=rand();if(a*a+b*b+r*r/4<a*r+b*r)c++;}return printf("%2.5f",c/n*4);}