After reaching the last ordered path, {TAIL ~ the first node} of {HEAD ~ each path} in the group is removed 
After reaching the last ordered path , { TAIL ~ the first node } of { HEAD ~ each path } in the group is removed
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH