how to display the last image of a file without kn

Question

I have an FTP server with 3 kind of photos:

a) the photos called c001, c002 ...
b) the photos called f001, f002 ...
c) the phots called 000abcd_date_time_ramdomnumber

I display in my website the first two with IMG SRC="c001.jpg" etc.

I would like to do the same with the third one displaying for instance the last 3, but I do not know how to do it

thanks for the advice - renato