Pay and discharge promptly when due all material obligations, all sales tax and all material taxes, assessments and governmental charges or levies imposed upon it or upon its income or profits or in respect of its property before the same shall become in default, as well as all material lawful claims for labor, materials and supplies or otherwise which, if unpaid, might become a Lien or charge upon such properties or any part thereof; provided, however, that it and each Subsidiary shall not be required to pay and discharge or to cause to be paid and discharged any such tax, assessment, charge, levy or claim so long as the validity or amount thereof shall be contested in good faith by appropriate proceedings and for which the Seller shall have set aside on its books adequate reserves with respect thereto.