using System;

public class Program

{

    public static void Main()

    {

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

        (numbers[0], numbers[1]) = (numbers[1], numbers[0]);

        foreach(var n in numbers)

        {

            Console.Write(n + " ");

        }

    }

}