As a result, the first resistor R1, in {HEAD ~ series} with the second resistor R2, is connected in parallel with {TAIL ~ the fourth resistor} R4 
As a result , the first resistor R1 , in { HEAD ~ series } with the second resistor R2 , is connected in parallel with { TAIL ~ the fourth resistor } R4
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH