20937	 { abs exch abs 2 copy add 1 gt {1 sub dup mul exch 1 sub dup mul add 1 sub }{ dup mul exch dup mul add 1 exch sub } ifelse } 
20938	{exch pop abs 1 exch sub}

20939	
counttomark dup 3 add -1 roll exch
2 sub mul dup floor cvi
dup 3 1 roll sub exch dup

20940	3 add index exch 2 add index dup
4 1 roll sub mul add

counttomark 1 add 1 roll cleartomark}