class WrongNumberException extends Exception {
    WrongNumberException(String msg) {
        super(msg);
    }
}

class Calculate {
    private int kerSzam() {
        return -9;
    }

    public void calc() throws WrongNumberException {
        int szam = kerSzam();

        if(szam<=0)
            throw new WrongNumberException("Hiba! Nem megfelelő szám!");
        else
            System.out.println("A szam: " + szam);
    }
}

class App {
    public static void main(String args[]) throws Exception {
        new Calculate().calc();
    }
}