using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

    static bool ContainsNearbyDuplicate(int[] nums, int k) {

        if (nums==null || nums.Length==00)

            return false;

        var d = new Dictionary<int,List<int>>();

        for (int i=0; i<nums.Length; i++)

        {

            var v = nums[i];

            if (!d.ContainsKey(v))

            {

                d.Add(v, new List<int>(){v});   

            }

            else

            {

                var l = d[v];

                for (int j = 0; j<l.Count;j++)

                {

                    if (Math.Abs(l[j]-v)==k)

                        return true;

                }

                l.Add(v);

            }

        }

        return false;

    }

}