#!/usr/bin/perl -l sub'z{print@_;$#_&&z(map{($_[$_-1]+$_[$_])=~/(.)(.)?/;$1+$2}1..$#_)}z pop=~/./g
#!/usr/bin/perl -l sub'z{print@_;$#_&&z(map{($_[$_-1]+$_[$_])=~/(.)(.)?/;$1+$2}1..$#_)}z split'',shift