Regeh

using System;
using System.Text.RegularExpressions;

namespace Regeh
{
    public class StartUp
    {
        public static void Main()
        {
            string input = Console.ReadLine();
            string result = string.Empty;
            int a = input.Length;
            string pattern = @"\[[a-zA-Z]+\<([0-9]+)REGEH([0-9]+)\>[A-Za-z]+\]";
            Regex regex = new Regex(pattern);
            MatchCollection matches = Regex.Matches(input, pattern);
            int nextIndex = 0;
            foreach (Match match in matches)
            {
                int firstIndex = int.Parse(match.Groups[1].ToString()) + nextIndex;
                int secondIndex = firstIndex + int.Parse(match.Groups[2].ToString());
                if (firstIndex > input.Length - 1)
                {
                    firstIndex = firstIndex % (input.Length - 1);
                }
                string firstLetter = input.Substring(firstIndex, 1);
                result += firstLetter;
                if (secondIndex > input.Length - 1)
                {
                    secondIndex = secondIndex % (input.Length - 1);
                }
                string secondLetter = input.Substring(secondIndex, 1);
                result += secondLetter;
                nextIndex = secondIndex;
            }
            Console.WriteLine(result);
        }
    }
}