package P6Course;

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        Map<String, TreeSet<String>> courses = new LinkedHashMap<>();

        String command;

        while (!"end".equals(command = scanner.nextLine())) {
            String[] data = command.split(" : ");
            String course = data[0];
            String student = data[1];

            courses.putIfAbsent(course, new TreeSet<>());
            courses.get(course).add(student);
        }

        courses
                .entrySet()
                .stream()
                .sorted((a, b) -> Integer.compare(b.getValue().size(), a.getValue().size()))
                .forEach(e -> {
                    System.out.println(e.getKey() + ": " + e.getValue().size());
                    e.getValue().forEach(u -> System.out.println("-- " + u));
                });
    }
}