open String let(!)=length let rec f?(s=read_line())b=let t=make(max!s!b)' 'in blit s 0t 0!s;for i=0to!b-1do t.[i]=' '&()=(t.[i]<-b.[i])done;print_endline t;f t;;f""
Note that non-ascii characters in the above source code will be escaped (such as \x9f).