01a.f (320B) - raw
1 2 variable last 3 : to-num ( a u -- n ) 0 -rot 0 do dup r@ + c@ h# 30 - rot 10 * + swap loop drop ; 4 : read-num ( -- n ) pad pad 10 accept to-num ; 5 : get-first-depth read-num last ! ; 6 : ?deeper dup last @ u> swap last ! ; 7 : count-deepers 1999 0 do read-num ?deeper if 1+ then loop ; 8 get-first-depth 0 count-deepers . cr bye