700 people are in a group. We'll use f to represent the first initial of their name, l for the first initial of their last name.

700 people are in a group. We'll use f to represent the first initial of their name, l for the first initial of their last name. Each person is identified with a pair (f,1). At least how many people from this group have the same pairs (f,1) of initials of their first and last name.