I've participated in a hacking competition in my school. I came up with a solution but i didn't knew how to code it so here am I asking for your help. 

The problem involved a security breach on a server. Files with gmail usernames:passw had been leaked and we, the infosec team, had to test which logins were compromised (if users hadn't changed their pw yet) to email them. So my idea was: first, cat all files using `cat * > merged-file`. Then, somehow create a mechanism to test each combination usr + pw on gmail putting a flag or creating another file with the successful ones. 

Sorry for my bad english, i'm not a native speaker.