How to use youtube-dl script to download starting from some index in a playlist?

youtube-dl --help, contains:

Video Selection:  --playlist-start NUMBER          Playlist video to start at (default is 1)  --playlist-end NUMBER            Playlist video to end at (default is last)  --playlist-items ITEM_SPEC       Playlist video items to download. Specify                                   indices of the videos in the playlist                                   separated by commas like: "--playlist-items                                   1,2,5,8" if you want to download videos                                   indexed 1, 2, 5, 8 in the playlist. You can                                   specify range: "--playlist-items                                   1-3,7,10-13", it will download the videos                                   at index 1, 2, 3, 7, 10, 11, 12 and 13.

Thus, the option --playlist-start NUMBER should help you to start the playlist in the middle, specified by NUMBER.

I have total 135 videos in my playlist. I have successfully downloaded 38 of them. So I manually used this command.

youtube-dl --playlist-start 39 -u uname@gmail.com -p mypassword https://www.udemy.com/learn-ethical-hacking-from-scratch/learn/v4/content

Its downloading my remaining 97 videos.