using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        int[] numbers1 = { 1, 2, 3 };

        int[] numbers2 = { 2, 3, 4, 5 };

​

        var AllElement = numbers1.Union(numbers2);  

        // Output results 

        foreach(var number in AllElement)

        {

            Console.WriteLine(number);

        }

    }

}