using System;

using System.Linq;

​

namespace ConsoleApp1

{

    public class Program

    {

        public static void Main(string[] args)

        {

            var input = "cqrsrsqqc";

            Console.WriteLine(MapAndReduceInputString(input));

        }

​

        private static string MapAndReduceInputString(string input)

        {

            var response = Enumerable.Range(0, input.Length / 3).Select(i => input.Substring(i * 3, 3).Select(c => MapToNumber(c)).Sum());

            return string.Join("", response.ToArray());

        }

​

        private static int MapToNumber(char c)

        {

            switch (c)

            {

                case 'c':

                    return 3;

​

                case 'q':

                    return 1;

​

                case 'r':

                    return 2;

​

                case 's':

                    return 0;

​

                default:

                    throw new Exception();

            }

        }

    }

}

​