using System;

public class Program

{

    public static void Main()

    {

            int[] numbers = { 1, 1, 2, 3 };

​

            for (var i = 0; i < numbers.Length; i++)

            {

                bool isDuplicate = false;

​

                for (var j = 0; j < i; j++)

                {

                    if (numbers[i] == numbers[j])

                    {

                        isDuplicate = true;

                        break;

                    }

                }

​

                if (isDuplicate == false)

                {

                    Console.WriteLine(numbers[i]);

                }

            }

    }

}