#!perl -l $_=pop;print,s/./$.=$?+$&;$?=$&;$.-9*($.>9)/eg,s/.//while/./
#!perl -l $_=pop;print,s/./$.=$?+$&;$?=$&;$.--&&$.%9+1/eg,s/.//while/./
#!perl -l $_=pop;print,s/./$.=$?+$&;$?=$&;$.--&&$.%9+1/eg,/./,$_=$' while/./