Problems(1)
Four integers are marked on a circle. On each step we simultaneously replace each number by the difference between this number and next number on the circle in a given direction (that is, the numbers a, b, c, d are replaced by a−b, b−c, c−d, d−a). Is it possible after 1996 such steps to have numbers a, b, c and d such that the numbers ∣bc−ad∣, ∣ac−bd∣ and ∣ab−cd∣ are primes?