ReGeXTaskLJ

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

public class Problem_12_LittleJohn
{
    public static void Main()
    {
        StringBuilder number = new StringBuilder();
        int smallArrows = 0;
        int middleArrows = 0;
        int largeArrows = 0;
        for (int i = 0; i < 4; i++)
        {
            string arrowRow = Console.ReadLine();
            string pattern = @"(>>>----->>)|(>>----->)|(>----->)";
            Regex rgx = new Regex(pattern);
            Match match = rgx.Match(arrowRow);
            while (match.Success)
            {
                string isMatch = match.Groups[1].Value;
                if (!string.IsNullOrEmpty(isMatch))
                {
                    largeArrows++;
                }
                isMatch = match.Groups[2].Value;
                if (!string.IsNullOrEmpty(isMatch))
                {
                    middleArrows++;
                }
                isMatch = match.Groups[3].Value;
                if (!string.IsNullOrEmpty(isMatch))
                {
                    smallArrows++;
                }

                match = match.NextMatch();
            }
        }

        if (smallArrows == 0 && middleArrows != 0)
        {
            number.Append(middleArrows);
            number.Append(largeArrows);
        }
        else if (smallArrows != 0 && middleArrows != 0)
        {
            number.Append(smallArrows);
            number.Append(middleArrows);
            number.Append(largeArrows);
        }
        else if (smallArrows != 0)
        {
            number.Append(smallArrows);
            number.Append(middleArrows);
            number.Append(largeArrows);
        }
        else
        {
            number.Append(largeArrows);
        }

        string bin = Convert.ToString(int.Parse(number.ToString()), 2);
        char[] binArr = bin.ToCharArray();
        Array.Reverse(binArr);
        StringBuilder joinedBin = new StringBuilder(bin + new string(binArr));
        int result = Convert.ToInt32(joinedBin.ToString(), 2);
        Console.WriteLine(result);
    }
}