/**
 * This program calculates pi using the monte carlo method
 * 
 * Mark Monarch
 * 2/26/15
 */
import java.util.Scanner;

public class piCalc
{
    public static void main()
    {
        // set up input
        Scanner in = new Scanner(System.in);
        
        // declare variables
        long    trials,
                inCircle = 0;
        double  x,
                y,
                piEstimate = 0;
        
        // asks user for number of trials. The more trials the more accurate
        System.out.print("Input number of trials: ");
        trials = in.nextLong();
        
        // run trials
        for (int i = 0; i < trials; i++)
        {
            x = Math.random();
            y = Math.random();
            if (x*x+y*y <= 1)
            {
                inCircle++;
            }
        }
        
        // Calculate pi
        piEstimate = 4 * (double) inCircle / (double) trials;
        
        // print results
        System.out.println("Pi is approximately: " + piEstimate);
    }
}