isempty =. (0 [ 0&{) :: 1:  NB. 0=#
   compare =. ($:&}.)`((0 1,:_1 0) {~ <@,&isempty)@.(+.&isempty) NB. *@-&#
   add =. ,`(,:@[)`] @. (compare {:)
   > add&.>/ (}: , ,:&.>@{:) ;: 'a bb ccc ddd ee f ggg'
ccc
ddd
ggg