Issue in picking a most recent file from ftp server

Hi Experts,

                    i had a requirement where i need to pick most recent file based on date and time in which we are getting multiple files for every hour.for Example :if a file is placed at11:00AM on 03/06/2015, with file name Activity.20150306.0010 our PI job will run at 11:05AM and it should pick file named Acitivity.20150306.1100.0010.txt. and i need to pick the most recent file and it has to be processed by the pi.please help me how to achieve this.

Thanks

Giridhar