my @dirs = File::Find::Rule
   ->directory()
   ->in('.');

for my $dir (@dirs) {
   my @rtfs = File::Find::Rule
      ->maxdepth(1)
      ->file()
      ->in($dir);

   for my $rtf (@rtfs) {
      ( my $ftp = $rtf ) =~ s/\.rtf\z/.ftp/;
      if (-e $ftp) {
         print("$rtf\n");
      }
   }
}