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"]);
}