using System;
public class Doubler
{
    private double num;
    public Doubler(double num)
    {
        this.num = num;
    }
    public double GetNum()
    {
        return num;
    }
    public void DoubleNum()
    {
        num = num * 2;
        Console.WriteLine("Doubled = {0}", num);
    }
    public void DoubleIt(Doubler it)
    {
        it.DoubleNum();
        Console.WriteLine("Doubled: it = {0}", it.GetNum());
    }
}// Doubler

public class DoublerTest
{
    public static void Main()
    {
        Doubler doubler1 = new Doubler(5);
        Doubler doubler2 = new Doubler(4);
        Console.WriteLine("doubler1 is {0}", doubler1.GetNum());
        doubler1.DoubleNum();
        Console.WriteLine("doubler1 after DoubleNum is {0}",
        doubler1.GetNum());
        Console.WriteLine("doubler2 is {0}", doubler2.GetNum());
        doubler1.DoubleIt(doubler2);
        Console.WriteLine("doubler2 after DoubleIt is {0}",
         doubler2.GetNum());
    } // Main
} //DoublerTest