Clearly, we need {TAIL ~ at least one target element} satisfying all of Requirements R1, R2, and {HEAD ~ R3} for each payload bit to be embedded 
Clearly , we need { TAIL ~ at least one target element } satisfying all of Requirements R1 , R2 , and { HEAD ~ R3 } for each payload bit to be embedded
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH