using System;

public class Program

{

    public static void Main()

    {

        int[] arr={1,99,1,1,3,2,8,4,1,2,9,5,7,2,6,0,5,3,7,4,7};

        Array.Sort(arr);

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

        {

            if(Array.IndexOf(arr,arr[i])!=Array.LastIndexOf(arr,arr[i]))

            {

                Console.WriteLine(arr[i]+" ");

                i=Array.LastIndexOf(arr,arr[i])+1;

            }

        }   

    }

}