using System;

        using System.Text;          

public class Program

{

    public static void Main()

    {

        string str = "abcd";

        int i = str.Length-1;

        StringBuilder sb = new StringBuilder(str);

        while(i > 0){

          sb.Insert(i, " ");

          i--;

        }   

        Console.Out.WriteLine(sb.ToString());

    }

}