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

class Program
{
    private static void Main()
    {
        var replaceCodes = new[] { "brown" ,"j" };
        var sb = new StringBuilder().Append("The quick bbrownbrownrown fox jumps over the lazy dog");
        var outStr = replaceCodes.Aggregate(sb, StringBilderCleaner).ToString();
        Console.WriteLine(outStr);
    }

    static StringBuilder StringBilderCleaner(StringBuilder sbStr, string rmStr)
    {
        var startIndex = 0;
        for (var i=0; i < sbStr.Length; i++)
        {
                var l = i - startIndex;
                if (l == rmStr.Length)
                {
                    sbStr.Remove(startIndex, l);
                    i=Math.Max(i-2*l-1,0); 
                    startIndex = i+1;
                }else
                if (rmStr[l] != sbStr[i])
        	    {
                if (l > 0) i--;
                startIndex = i + 1;
                }
        }
        return sbStr;
    }
}