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