Thus, retailers obtain {TAIL ~ full price} for {HEAD ~ products} purchased with the exchange system coupons 
Thus , retailers obtain { TAIL ~ full price } for { HEAD ~ products } purchased with the exchange system coupons
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH