How to create a filter that moves incoming emails with no subject to a specified folder?

How to create a filter that moves incoming emails with no subject to a specified folder?

What should I enter in the condition field?

I've tried:
  1. Empty field -> result is: "Provide some criteria"
  2. "" -> result is: filter is not created at all, and clicking the "Save" button has no effect nor raises any errors
  3. '' -> result is: filter is not created at all, and clicking the "Save" button has no effect nor raises any errors
  4. (No Subject) -> result is: filter is created, but emails with the subject "(No Subject)" are moved to a specified folder
I also tried exporting the filter with the "(No Subject)" condition and changing the line

condition=" AND (subject,is,(No Subject))"

to:
  1. condition=" AND (subject,is,)"
  2. condition=" AND (subject,is,"")"
  3. condition=" AND (subject,is,'')"
but every time when I tried to import the filter back (before that I deleted the old filter from Filters, filter exported earlier), in every case I just get notification "There are no filters in the selected file to import!" until I change the line back to

condition=" AND (subject,is,(No Subject))"

and then after importing the filter back I get notification "Filters have been imported." but condition is now just "No Subject" (without parentheses "()") and now emails with the subject "No Subject" are moved to a specified folder.

Help pages Filters and Incoming Filter doesn't provide any help for this case.

Is it even possible to filter incoming emails with no subject in Zoho Mail email filters?

Thanks