abstract class Race{}
class MordorUnit extends Race{}
class MiddleEarthUnit extends Race{}

interface Unit<T> {}

interface Infantry<T> extends Unit{}
interface Cavalry<T> extends Unit{}


public class Army<T extends Race> {
    private ArrayList<Cavalry<T>> cavalry = new ArrayList<>();
    private ArrayList<Infantry<T>> infantry = new ArrayList<>();
    private ArrayList<Unit> army = new ArrayList<>();

    public ArrayList<Cavalry<T>> getCavalry() {
        return cavalry;
    }

    public ArrayList<Infantry<T>> getInfantry() {
        return infantry;
    }

    public ArrayList<Unit> getArmy() {
        return army;
    }

    public boolean recruit(Unit<T> unit) {
        if (unit instanceof Infantry){
            army.add(unit);
            return infantry.add((Infantry) unit);
        }
        if (unit instanceof Cavalry){
            army.add(unit);
            return cavalry.add((Cavalry) unit);
        }

        return false;
    }

    public boolean release(Unit unit) {
        if (cavalry.contains(unit)){
            army.remove(unit);
            return cavalry.remove(unit);
        }
        if (infantry.contains(unit)){
            army.remove(unit);
            return infantry.remove(unit);
        }
        return false;
    }

    public void print() {
        army.stream().filter(x -> x instanceof Cavalry).forEach(x -> System.out.print(x.toString() + "\n"));
        army.stream().filter(x -> x instanceof Infantry).forEach(x -> System.out.print(x.toString() + "\n"));
    }

    public Unit getRandomUnit() {
        return army.get((int) (Math.random() * army.size()));
    }

    public Unit getRandomUnit(Unit unit) {
        if (unit instanceof Cavalry) cavalry.get((int) (Math.random() * cavalry.size()));
        if (unit instanceof Infantry) infantry.get((int) (Math.random() * infantry.size()));
        return null;
    }
}