demo

package PastFinalExams.finexam;

import java.util.*;

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

        Map<String, List<String>> usersInfo = new LinkedHashMap<>();
        Map<String, Integer> sentEmails = new LinkedHashMap<>();

        String command;
        while (!(command = scanner.nextLine()).equals("Statistics")) {
            String[] tokens = command.split("->");
            String subCommand = tokens[0];
            String username = tokens[1];
            int sentCount = 0;

            switch (subCommand) {

                case "Add":
                    if (usersInfo.containsKey(username)) {
                        System.out.println(String.format("%s is already registered", username));
                    } else {
                        usersInfo.put(username, new ArrayList<>());
                    }
                    /*List<String> sentEmails = usersInfo.get(username);
                    if (!sentEmails.contains(usersInfo.get(username))) {
                        sentEmails.add(username);
                    }
                    */
                    break;
                case "Send":
                    String email = tokens[2];
                    sentEmails.put(username, 1);
                    List<String> sentList = usersInfo.get(username);
                    usersInfo.get(username).add(email);
                    break;
                case "Delete":
                    if (usersInfo.containsKey(username)) {
                        usersInfo.remove(username);
                    } else {
                        System.out.println(String.format("%s not found!", username));
                    }
                    break;
            }
        }
        System.out.println(String.format("Users count: %d", usersInfo.size()));


        sentEmails
                .entrySet()
                .stream()
                .sorted((a, b) -> {
                    int result = b.getValue().compareTo(a.getValue());
                    if (result == 0) {
                        result = a.getKey().compareTo(b.getKey());
                    }
                    return result;
                }).forEach(e -> {
                    System.out.println(e.getKey());
        });

        for (String user : usersInfo) {
            System.out.println(String.format("- %s", sentEmails));
    }
}