using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace courses
{
    class Program
    {
        static void Main()
        {
            string command = Console.ReadLine();
            var coursesList = new Dictionary<string, List<string>>();
            while (command!="end")
            {
                List<string> commandInput = command.Split(" : ").ToList();
                string courseName = commandInput[0];
                string studentName = commandInput[1];
                if (!coursesList.ContainsKey(courseName))
                {
                    coursesList[courseName] = new List<string>();
                }
                coursesList[courseName].Add(studentName);
                command = Console.ReadLine();
            }
            coursesList.OrderBy(x => x.Value.Count);
            foreach (var course in coursesList)
            {
                course.Value.Sort();
                int studentsCount = course.Value.Count;
                Console.WriteLine($"{course.Key}: {studentsCount}");
                for (int i = 0; i < course.Value.Count; i++)
                {
                    Console.WriteLine($"-- {course.Value[i]}");
                }
            }
        }
    }
}