"16,11,15,0,1,7" "," split [ string>number ] map
[ but-last [ 2array ] map-index >hashtable ] [ last ] [ length 1 - ] tri
 dup 30000000 1 - swap - [ 2over swap at [ 3dup swap rot set-at ] dip 
[ [ - nip ] keepd ]
[ [ drop 0 ] dip ]  if* 1 + ] times
drop nip .