Build an iMacro bot to search the Facebook API for users. Simply have the bot pull the URL's from a notepad list, make a "GET" request to the Facebook API URL and you'll get the following:
{
"id": "394849575",
"name": "Brian Johnson",
"first_name": "Brian",
"last_name": "Johnson",
"link": "facebook.com/Brian",
"username": "Brian",
"gender": "male",
"locale": "en_US",
"updated_time": "",
"type": "user"
}
Your "Get ID" is what you're looking for, have the ID extracted to a list and repeat the process.