1701 string 50{(%stdin)(r)file dup read{dup 73 idiv sub 20 mul exch token pop
add 2 copy 1 put}if pop}repeat 99 1 1680{2 copy get 1 xor 1 index 20 mod mul
0[1 -1 20 -20]{3 index add 4 index exch get add}forall mul{( )dup 0 3 index 20
idiv dup 73 idiv add put print 20 mod =[exit}repeat pop}for