using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        var accounts = new Dictionary<string, double>();

        // Initialise to zero...

        accounts["Fred"] = 0;       // Equivalent to accounts.Add("Fred", 0);

        accounts["George"] = 0;     // Equivalent to accounts.Add("George", 0);

        // Add cash.

        accounts["Fred"] += 4.56;

        accounts["George"] += 1.00;

        accounts["Fred"] += 1.00;

        Console.WriteLine("Fred owes me ${0}", accounts["Fred"]);

    }

}