мерлин

using System;
using System.Text;
using System.Text.RegularExpressions;

class MainClass
{
  public static void Main (string[] args)
  {
    int index = 0;
    string merl = @"^Merlin\s*speaks";
    string kill = @"Avada-ke-davra";
    string str = Console.ReadLine();

    while(true)
    {
      index = index + 1;
      var merlin = Regex.Match(str, merl);
        if(merlin.Success)
            foreach (Match match in Regex.Matches(str, kill))
                 Console.WriteLine($"{index} {match.Index + 1}");

          str = Console.ReadLine();
          if (String.IsNullOrEmpty(str))
           break;
   }
 }
}