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

double random() {
  return rand()/(RAND_MAX + 1.0);
}

int main(void) {
  srand(time(0));
  
  int i, stPoskusov = 1e6, stUgodnih = 0;
  double p, x, y;
  
  for (i=0; i<stPoskusov; i++) {
    y = random();
    x = random();
    if (x*x + y*y <= 1.0) stUgodnih++;
  }
  
  p = 1.0 * stUgodnih / stPoskusov;
  printf("4p = %lf\n", 4.0*p);
  
  return 0;
}