03. Inbox Manager

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        HashMap<String, ArrayList<String>> users = new HashMap<>();

        String input = scan.nextLine();
        while (!"Statistics".equals(input)) {
            String[] tokens = input.split("->");
            String command = tokens[0];
            String username = tokens[1];

            switch (command) {
                case "Add":
                    if (users.containsKey(username)) {
                        System.out.println(String.format("%s is already registered", username));
                    } else {
                        users.put(username, new ArrayList<>());
                    }
                    break;
                case "Send":
                    String email = tokens[2];
                    ArrayList<String> emails = users.get(username);
                    emails.add(email);
                    break;
                case "Delete":
                    if (users.containsKey(username)) {
                        users.remove(username);
                    } else {
                        System.out.println(String.format("%s not found!", username));
                    }
                    break;
            }

            input = scan.nextLine();
        }

        System.out.println(String.format("Users count: %d", users.size()));
        users
                .entrySet()
                .stream()
                .sorted((u1, u2) -> {
                    int result = u2.getValue().size() - u1.getValue().size();
                    if (result == 0) { // Ния
                        result = u1.getKey().compareTo(u2.getKey());
                    }
                    return result;
                })
                .forEach(u -> {
                    System.out.println(u.getKey());
                    u.getValue().forEach(e -> System.out.println(String.format(" - %s", e)));
                });
    }
}