class PartyC {
    public static void main(String[] arg) {
        CoffeeCupC c1 = new CoffeeCupC();
        CoffeeCupC c2 = new CoffeeCupC();
        c1.amount = CoffeeCupC.volume;
        c2.amount = CoffeeCupC.volume;
        c1.amount -= 20;
    }
}