using System;

using System.Collections.Generic;

using System.Text;

​

public class Program

{

    public static void Main()

    {

          int[] arr = { 4, 2, 1, 3, 2, 1, 5, 4, 6, 3 };

          int uniqueIndex =0;

          HashSet<int> seen = new HashSet<int>();

          foreach(int ele in arr)

          {

              if(!seen.Contains(ele))

              {

                  seen.Add(ele);

                  arr[uniqueIndex] = ele;

                  uniqueIndex++;

              }   

          }

        for(int k=0;k<uniqueIndex;k++)

        {

            Console.WriteLine($"{arr[k]}");

        }

    }

}