import Mathlib.Init.Data.Int.CompLemmas
import Mathlib.Data.Int.ModEq
import Mathlib.Tactic

/-!
# International Mathematical Olympiad 2007, Problem 5

Let a and b be positive integers. Show that if 4ab - 1 divides (4a² - 1)²
then a = b.
-/

namespace Imo2007P5

theorem imo2007_p5 (a b : ℤ) (ha : 0 < a) (hb : 0 < b)
    (hab : 4 * a * b - 1 ∣ (4 * a^2 - 1)^2) : a = b := sorry

This problem has a complete solution written by Gian Sanjaya.

The solution was imported from imo-A-and-N/src/IMO2007/N6/N6.lean.