using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;

namespace ConsoleApp11
{
    class Program
    {
        static void Main(string[] args)
        {
            string defaultString = "A moving line";
            while (true)
            {
                int i = 0;
                if (i % 2 == 0)
                {
                    for (int a = 7; a <= 20; a++)
                    {
                        WriteTextInPosition(defaultString, a);
                        Thread.Sleep(42);
                    }
                }
                i++;
                if (i % 2 != 0)
                {
                    for (int a = 19; a > 7; a--)
                    {
                        WriteTextInPosition(defaultString, a);
                        Thread.Sleep(42);
                    }
                }
            }
        }

        public static void WriteTextInPosition(string text, int bot)
        {
                Console.Clear();
                for (int i = 1; i <= bot; i++)
                {
                    Console.WriteLine();
                }
                Console.WriteLine(String.Format("{0," + ((Console.WindowWidth / 2) + (text.Length / 2)) + "}", text));
        }
    }
}