using System;

public class Program

{

    public static void Main()

    {

        var dict = new System.Collections.Generic.Dictionary<string, int>();

        dict["a"] = 5;

        dict["b"] = 10;

        dict["a"] = 1;

        foreach(var d in dict)

        {

            Console.WriteLine(d.Key + "   " + d.Value);

        }

    }

}