using System;

public class Program

{

    public static void Main()

    {

        for (long i = 10; i < 10000000000; i*=10){

            double d = Estimate_pi(i);

            Console.WriteLine($"{i} => {d}");

        }

    }

    public static double Estimate_pi(long n){

        long pointCircle = 0;

        long pointTotal = 0;

        Random rand = new Random();

        for (long i = 0; i < n; i++){

            double x = rand.NextDouble();

            //Console.WriteLine(x);

            double y = rand.NextDouble();

            //Console.WriteLine(y);

            double distance = Math.Pow(x, 2) + Math.Pow(y, 2);

            //Console.WriteLine(distance);

            if ( distance <= 1)

                pointCircle++;

            pointTotal++;                       

        }

        //Console.WriteLine($"pointCircle {pointCircle}");

        //Console.WriteLine($"pointTotal {pointTotal}");

        return 4.00 * pointCircle/pointTotal;

    }

}