my $fi = scalar (@FILES);
for (my $k = 0; $k < $fi ; $k++)
  {
     open (F,$FILES[$k]) or die " rey ledhu ra \n";
     ...
  };

##</code><code>##

foreach my $file ( @FILES )
{
    open my $inFH, '<', $file
       or die "open: < $file: $!\n";
    ...
}