import java.util.ArrayList;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class Monitor {
    private ArrayList<Kniv> kniver = new ArrayList<>();
    private ArrayList<Saks> sakser = new ArrayList<>();
    private Lock lock = new ReentrantLock();

    public void settInn(Kniv k) {
        lock.lock();
        try {
            kniver.add(k);
        }
        finally {
            lock.unlock();
        }
    }

    public Kniv[] taUtToKniver() {
        lock.lock();
        try {
            if (hentAntallKniver() < 2) return null;
            Kniv[] ut = {kniver.remove(0), kniver.remove(0)};
            return ut;
        } finally {
            lock.unlock();
        }
    }

    public int hentAntallKniver() {
        return kniver.size();
    }

    public void settInn(Saks s) {
        lock.lock();
        try {
            sakser.add(s);
        }
        finally {
            lock.unlock();
        }
    }

    public int hentAntallSakser() {
        return sakser.size();
    }
}