using System;
using System.Collections.Generic;
using System.Linq;

namespace HomeTesting
{
    public class University
    {
        public static void Main()
        {
            string[] command = Console.ReadLine().Split(':');
            string course = command[0];

            var courseInformation = new Dictionary<string, List<string>>();

            while (course != "end")
            {
                var student = command[1];

                if (!courseInformation.ContainsKey(course))
                {
                    courseInformation.Add(course, new List<string> { student });
                }
                else
                {
                    courseInformation[course].Add(student);
                }

                command = Console.ReadLine().Split(':');
                course = command[0];
            }

            var sortedInfo = courseInformation
                .OrderByDescending(p => p.Value.Count)
                .ToDictionary(
                    p => p.Key,
                    p => (IList<string>)p.Value.OrderBy(n => n).ToList()
                );

            foreach (var pair in sortedInfo)
            {
                Console.WriteLine($"{pair.Key.Trim()}: {pair.Value.Count}");
                Console.WriteLine($"--{String.Join(" ", pair.Value)}");
            }
        }
    }
}