Neither the first input signal nor {HEAD ~ the second input signal} are applied to a base or gate of {TAIL ~ the fourth transistor} 
Neither the first input signal nor { HEAD ~ the second input signal } are applied to a base or gate of { TAIL ~ the fourth transistor }
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL