Mine

        public List<int> digits = new List<int>();
        public List<string> words = new List<string>();

        public int GetDigitsLength(string line)
        {   
            int i1 = 0;
            for(int i = 0; i < line.Length; i++) {
                if (char.IsDigit(line[i]))
                    i1++;
                else
                    return i1;
            }
            return i1;
        }

        public string ParseLines(string[] lines)
        {
            for (int i = 0; i < lines.Length; i++)
            {
                int l = GetDigitsLength(lines[i]);
                int digit = int.Parse(lines[i].Remove(l));
                if (!digits.Contains(digit))
                {
                    words.Add(lines[i].Substring(l));
                    digits.Add(digit);
                }
            }
            string output = "";
            for (int i2 = 0; i2 < words.Count; i2++)
            {
                output += words[i2]+"\r\n";
            }
            return output;
        }