hw

            string maxLetters = "";
            int maxIndex = 0, seq = 0;
            char ch, last;
            int[] letters = new int[26];
            ch = char.Parse(Console.ReadLine());
            last = ch;
            while (ch != '*')
            {
                if (ch == last)
                    seq++;
                else
                {
                    letters[last - 'a'] = Math.Max(letters[last - 'a'], seq);
                    seq = 1;
                }
                last = ch;
                ch = char.Parse(Console.ReadLine());
            }
            letters[last - 'a'] = Math.Max(letters[last - 'a'], seq);
            for (int i = 0; i < letters.Length; i++)
            {
                if (letters[i] > 0)
                {
                    Console.Write("({0},{1}) , ", (char)(i + 'a'), letters[i]);
                    if (letters[i] > letters[maxIndex])
                    {
                        maxIndex = i;
                        maxLetters = ((char)(i + 'a')).ToString();
                    }
                    else if (letters[i] == letters[maxIndex])
                        maxLetters += " , " + (char)(i + 'a');
                }
            }
            Console.WriteLine("/n" +maxLetters);