Twenty-five people of different heights stand in a 5 \times 5 grid of squares, with one person in each square. We know that each row has a shortest person; suppose Ana is the tallest of these five people. Similarly, we know that each column has a tallest person; suppose Bev is the shortest of these five people.
Assuming Ana and Bev are not the same person, who is taller: Ana or Bev? Prove that your answer is always correct.