// This program computes an approximation to pi using what is known as a
// "Monte Carlo technique."  The program picks random points in the unit
// square and counts how many are in the unit circle.  The probability of
// falling in the unit circle is pi/4, so we multiply the ratio by 4 to get
// an approximation to pi.

import java.util.*;

public class ComputePi {
    public static void main(String[] args) {
        Scanner console = new Scanner(System.in);
        Random r = new Random();
        System.out.print("times? ");
        int times = console.nextInt();
        int count = 0;
        for (int i = 1; i <= times; i++) {
            double x = r.nextDouble();
            double y = r.nextDouble();
            if (x * x + y * y <= 1) {
                count++;
            }
        }
        double estimate = 4.0 * (double) count / (double) times;
        System.out.println("estimate = " + estimate);
        System.out.println("let's cheat, pi = " + Math.PI);
    }
}