public static boolean subtract() {
        if ( calcStack.getCount() < 1 ) {
            calcStack.printEmptyMsg();
            return false;
        }
        else if ( calcStack.getCount() == 1) {
            x = calcStack.pop();
            y = 0;
        }
        else {
            popTwo();
        }

        double result = y - x;
        pushResult(result);
        return true;
    }