private void increaseScore(int a) {
        if (level >= 5 && level <= 7) {
            a *= 2;
        } else if (level <= 10) {
            a *= 3;
        } else if (level == 11) {
            a *= 4;
        } else if (level == 12) {
            a *= 5;
        } else if (level == 13) {
            a *= 10;
        } else if (level == 14) {
            a *= 30;
        } else if (level == 15) {
            a *= 100;
        }
        score += a;
        setChanged();
        notifyObservers(score);
    }