import java.util.*;

public class PhonebookHashApp
{
    public static int hashFunction(String name){
        int hash = 0;
        for(int i=0; i<name.length(); i++){
            hash = hash*10 + name.charAt(i);
        }
        hash = hash % 499;
        return hash;
    }

    public static void main(String[] args){
        Hashtable<Integer, String> phonebook = new Hashtable<>();
        List<String> names = new ArrayList<>();
        Scanner sc = new Scanner(System.in);

        int choice = -1;
        String number;
        String name;
        while(choice != 0){
            System.out.println("Silahkan pilih:\n1. Tambahkan kontak\n2. Cari kontak\n3. Hapus kontak\n4. Lihat semua\n0. Keluar");
            choice = sc.nextInt();
            switch(choice){
                case 1:
                    System.out.println("Masukkan nomor telepon:");
                    number = sc.next();
                    System.out.println("Masukkan nama kontak:");
                    name = sc.next();
                    names.add(name);
                    phonebook.put(hashFunction(name), number);
                    System.out.println("Kontak telah ditambahkan");
                    break;
                case 2:
                    System.out.println("Masukkan nama kontak:");
                    name = sc.next();
                    number = phonebook.get(hashFunction(name));
                    System.out.println("Nomor telepon: " +  number);
                    break;
                case 3:
                    System.out.println("Masukkan nama kontak:");
                    name = sc.next();
                    names.remove(name);
                    phonebook.remove(hashFunction(name));
                    System.out.println("Kontak telah dihapus");
                    break;
                case 4:
                    if(phonebook.size() > 0){
                        System.out.println(phonebook.size() + " kontak tersimpan");
                        for(String i : names){
                            System.out.println(i + ": " + phonebook.get(hashFunction(i)));
                        }
                    }
                    else
                        System.out.println("Tidak ada kontak yang tersimpan");
            }
        }
    }
}