#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main() {
  double x, y;
  int nc, nq;
  int i;
  int N = 10000000;
  double R, R2;
  
  R = 0.7;
  R2=R*R;
  
  nc = 0;
  nq = 0;
  for (i=0; i<N; i++) {
    x =drand48();
    y = drand48();
    if (x*x+y*y<R2) {
      nc ++;
    }
    nq ++;
  }
  printf("%f (%f)\n", 4.*nc/nq/R2, M_PI);
}