What parts are you having trouble with?

• Use "open" top open the file
• Use "< ... >" to read from the file
• USe "split" to break each line into its parts
• Use a hash to store the filename
• Only print filenames if they don't exist in the hash

Update: I deliberately didn't give any code as I don't like to help people who show no sign of putting any effort in for themselves. It seems that others don't agree with that policy.