interface Function<R> {
    public R call(Object... args);
}

abstract class Function1<R, A> implements Function<R> {
    abstract public R call(A arg1);
    public R call(Object... args) {
        System.out.println("call: Generic");
        return call((A)args[0]);
    }
}

class TestFunc extends Function1<Integer, Integer> {
    public Integer call(Integer a) {
        System.out.println("call: Real");
        return a+2;
    }
}

class main {
    public static void main(String[] args) {
            Function<Integer> f = new TestFunc();
            TestFunc f2 = (TestFunc)f;
            Integer a = f.call(11);
            System.out.println(a);
            Integer b = f2.call(12);
            System.out.println(b);
    }
}