Školjka

%V0 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, moving in a clockwise 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 to have numbers $a,b,c,d$ such the numbers $|bc-ad|, |ac - bd|, |ab - cd|$ are primes?