@g=map{$_=sprintf"%04o",$_;$_=~y@0-7@A-H@;$_}0..4095;for($|=
1;@g>0;){print$f=splice(@g,@g*rand,1),$";($S=<>)=~/^[0-4]{2}$
/?(@g=grep{$d=4-($a=($f^($e=$_))=~y@\0@@);$d-=($c=index$e,$_)<
0||(substr($e,$c,1)="")for(split'',$f);$&eq$a.$d}@g):print"\7"}

##</code><code>##

@g=map{$_=sprintf"%04o",$_;$_=~y@0-7@A-H@;$_}0..4095;for($|=1;@
g>0;){print$f=splice(@g,@g*rand,1),$";($S=<>)=~/^[0-4]{2}$/?(@
g=grep{$d=4-($a=($f^($e=$_))=~y@\0@@);$d-=($c=index$e,$_)<0||
(substr($e,$c,1)="")for(split'',$f);$&eq$a.$d}@g):print"\7"}