using System;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var set1 = new[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

        var set2 = new[] { 2, 4, 6, 8, 10 };

        var result = set1.Concat(set2);

        foreach (var r in result)

        {

            Console.Write(r + " ");

        }

    }

}