Little John - using LINQ

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

public class LittleJohn
{
    public static void Main()
    {
        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < 4; i++)
        {
            sb.AppendFormat(" {0}", Console.ReadLine());
        }

        const string ArrowPattern = @"(>>>----->>)|(>>----->)|(>----->)";

        Regex arrowMatcher = new Regex(ArrowPattern);

        var arrows = arrowMatcher.Matches(sb.ToString()).Cast<Match>();

        int largeArrowCount = arrows.Count(match => match.Groups[1].Value != string.Empty);
        int mediumArrowCount = arrows.Count(match => match.Groups[2].Value != string.Empty);
        int smallArrowCount = arrows.Count(match => match.Groups[3].Value != string.Empty);

        string numberAsString = string.Format(
            "{0}{1}{2}",
            smallArrowCount,
            mediumArrowCount,
            largeArrowCount);

        int number = int.Parse(numberAsString);

        string binaryNum = Convert.ToString(number, 2);

        string reversedBinaryNum = new string(binaryNum.Reverse().ToArray());

        string resultAsString = binaryNum + reversedBinaryNum;

        int result = Convert.ToInt32(resultAsString, 2);

        Console.WriteLine(result);
    }
}