using System;

using System.Collections;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

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

        Random rd = new Random();

        int rand_num = rd.Next(1,1000);

        using arr.Remove(5);

        int j = arr[0];

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

            if(j == arr[i]){

                j++;

                continue;

            }

            else

            {

                Console.WriteLine($"{j} {rand_num}");

                break;

            }

        }

    }

}