sub f {
#        1         2         3         4         5
#234567890123456789012345678901234567890123456789012345
my%h;$h{$_}++for@_;my@b;push @{$b[length]},$_ for grep{
#    6        7         8         9         0         1
#789012345678901234567890123456789012345678901234567890123
my%g=%h;$g{$_}--for/./gi;!grep{$_<0}values%g}<D>;@{$b[-1]}
}