using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Dictionary<string,string> dic = new Dictionary<string,string>();

        dic["XYZ"] = "123";

        dic["XYZ"] = "345";

        Console.WriteLine("{0}",dic["XYZ"]);

        dic.Add("ABC","123");

        dic.Add("ABC","789");

        Console.WriteLine("{0}",dic["ABC"]);

    }

}