$"=$_;map{binmode$_}\*STDIN,\*STDOUT;sub r{my($n,$s,$t,$c)=@_;$c=$$n[0];return
$,++,$_{$c}=$s,push@0,pack"aCB16",$c,$t,$s if!ref($c);map r($$c[$_],$s.$_,$t+1
),0,1}sub h{$/=\1;$0{$_}++,$;.=$_ while<>;@_=map[$_,$0{$_}],keys%0;while(@_>1)
{@_=sort{$$b[1]<=>$$a[1]}@_;$l=pop;$r=pop;push@_,[[$l,$r],$$l[1]+$$r[1]]}r pop
;$;=~s/./$_{$&}/gs;chr($,)."@0".pack("SB*",$.,$;)}print h