class ModdedXOR
    {
        public static string encrypt(string input) {
            char[] key = {'R', 'C', 'E'};
            char[] output = new char[input.Length];

            for(int i = 0; i < input.Length; i++) {
                //data[i] = data[i] ^ data[i+1] ^ key;
               output[i] = (char)(input[i] ^ input[i + 1] ^ key[i % key.Length]);
            }
            return new string(output);
        }

    }