The Secretary may prescribe a sum which shall be credited to each new cadet upon first admission to the Academy, to cover the cost of his initial clothing and equipment issue, which sum shall be deducted subsequently from his pay. Each cadet discharged prior to graduation who is indebted to the United States on account of advances of pay to purchase required clothing and equipment shall be required to turn in to the Academy all clothing and equipment of a distinctively military nature to the extent required to discharge such indebtedness; and, if the value of such clothing and equipment so turned in does not cover the indebtedness incurred, then such indebtedness shall be canceled.