using System;

class IndexExample
{
  string Message;

  public static void Main()
  {
    IndexExample obj=new IndexExample("Welcome");

  
    for(int i=0;i < obj.Length;i++)
    {
      Console.WriteLine(obj[i]);
    }
    
   obj[obj.Length-1]="Test";

    Console.WriteLine(obj.Message);

  }

  public IndexExample(string s)
  {
    Message=s;
  }

  public string this[int i]
  {
    get
    {
      if(i >= 0 && i < Message.Length)
      {
        return Message.Substring(i,1);
      }
      else
      {
        return "";        
      }
    }
    set
    {
      if(i >= 0 && i < Message.Length)
      {
        Message=Message.Substring(0,i) + value + Message.Substring(i+1);
      }
    }
  }

  public int Length
  {
    get
    {
      if(Message!=null)
      {
        return Message.Length;
      }
      else
        return 0;
    }
  }
}