Section 24. Common expenses a charge.

All sums assessed by the association but unpaid for the share of the common expenses chargeable to any apartment, shall constitute a charge on such apartment, prior to all other charges, except only,- (a) the charge, if any, on the apartment for payment of government and municipal taxes; (b) all sums unpaid on a first mortgage of the apartment; (e) any instalment due but unpaid under the hire -purchase agreement; and (d) arrears of ground rent and other charges payable to the lessor.