Decode

public string Decoding()
        {
            StringBuilder newtext = new StringBuilder();
            StringBuilder line = new StringBuilder();
            var slovar = new Dictionary<string, char>();
            slovar = CodingDict.ToDictionary(x => x.Value, x => x.Key);
            for (int i = 1; i < EncodingText.Length; i++)
            {
               line.Append(EncodingText[i]);
                string symbol = line.ToString();
                if (slovar.ContainsKey(symbol))
                {
                    newtext.Append(slovar[symbol]);
                    line.Clear();
                }
            }
            return newtext.ToString();