foreach $i (@f) {
        @e = grep {$_ % $i != 0}  @n;
        @n = ();
        @n = @e;
}
##</code><code>##

foreach $i (@f) {
  @n = grep {$_ % $i != 0} @n;
}

##</code><code>##

foreach $i (@f) {
  @n = grep {$_ % $i != 0 || $_ == $i} @n;
}