How to display the last image of a file without knowing the image name <IMG SRC

Question

I have an FTP server with 3 photos:

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

I display the first two on my website with IMG src = "c001.jpg" etc.

I would like to do the same with a third, displaying, for example, the last 3, but I do not know how to do this

thanks for the advice - renato