sub f {
#        1         2         3         4         5         6         7
#2345678901234567890123456789012345678901234567890123456789012345678901234567890
for(<D>){$n=0;$o=$_;for$c(@_){$n+=s/$c//};push@{$w[$n]},$o if/^$/;}@{$w[-1]}
}