{HEAD ~ The exchange system} invalidates a conventional coupon and prints an exchange system coupon for a product promoted by {TAIL ~ the coupon exchange system} 
{ HEAD ~ The exchange system } invalidates a conventional coupon and prints an exchange system coupon for a product promoted by { TAIL ~ the coupon exchange system }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL