using System;

using System.Collections;

using System.Collections.Generic;

using System.Collections.Concurrent;

public class Program

{

    public static void Main()

    {

        var concurrentDict = new ConcurrentDictionary<int, string>();

        concurrentDict[1] = "Hello";

        concurrentDict[int.MaxValue] = "World";

        foreach(var pair in concurrentDict)

        {

            Console.WriteLine(pair.Value);

        }       

        var concurrentDictList = new ConcurrentDictionary<string, List<string>>();

        concurrentDictList["1"] = new List<string>{"Hello"};

        concurrentDictList["int.MaxValue"] = new List<string>{"World"};

        concurrentDictList["1"].Add("Bier");

        if(!concurrentDictList.ContainsKey("Kaffee"))

            concurrentDictList["Kaffee"] =  new List<string>();

        concurrentDictList["Kaffee"].Add("Arabica");

        foreach(var pair in concurrentDictList)

        {

            Console.WriteLine(String.Join(", ", pair.Value));

        }       

    }

}