Method Overriding And Increment Operators

What is printed when the following program is executed?

class Number {
    int x = 10;
    int update() { return x++; }
}

class SubNumber extends Number {
    int update() { return ++x + super.update(); }
    public static void main(String[] args) {
        SubNumber sn = new SubNumber();
        System.out.println(sn.update());
    }
}