Hero

import java.util.*;

public class ex3 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String input = scanner.nextLine();
        Map<String, List<String>> heroes = new HashMap<>();
        while (!"End".equals(input)) {
            String[] tokens = input.split(" ");
            String command = tokens[0];
            String heroName = tokens[1];
            switch (command) {
                case "Enroll": {
                    if (!heroExists(heroName, heroes)) {
                        heroes.put(heroName, new ArrayList<>());
                    } else {
                        System.out.println(String.format("%s is already enrolled.", heroName));
                    }
                    break;
                }
                case "Learn": {
                    String spell = tokens[2];
                    if (heroExists(heroName, heroes)) {
                        if (heroes.get(heroName).contains(spell)) {
                            System.out.println(String.format("%s has already learnt %s.", heroName, spell));
                        } else {
                            heroes.get(heroName).add(spell);
                        }
                    } else {
                        System.out.println(String.format("%s doesn't exist.", heroName));
                    }
                    break;
                }
                case "Unlearn": {
                    String spell = tokens[2];
                    if (heroExists(heroName, heroes)) {
                        if (heroes.get(heroName).contains(spell)) {
                            heroes.get(heroName).remove(spell);
                        } else {
                            System.out.println(String.format("%s doesn't know %s.", heroName, spell));

                        }
                    } else {
                        System.out.println(String.format("%s doesn't exist.", heroName));
                    }
                    break;
                }
            }

            input = scanner.nextLine();
        }
        System.out.println("Heroes:");
        heroes.entrySet().stream()
                .sorted((a, b) ->
                        {
                            int sizeA = a.getValue().size();
                            int sizeB = b.getValue().size();
                            String nameA = a.getKey();
                            String nameB = b.getKey();
                            if (sizeA != sizeB) {
                                return Integer.compare(sizeA, sizeB);
                            } else {
                                return nameA.compareTo(nameB);
                            }
                        }
                ).forEach(entry -> {
            System.out.printf("== %s: ", entry.getKey());
            System.out.printf(String.join(", ", entry.getValue()));
            System.out.println();
        });
    }

    private static boolean heroExists(String command, Map<String, List<String>> heroes) {
        if (heroes.containsKey(command)) {
            return true;
        }
        return false;
    }
}