9.8. Find the minimum value of the expression

$(\sqrt{2(1+\cos 2 x)}-\sqrt{9-\sqrt{7}} \sin x+1) \cdot(3+2 \sqrt{13-\sqrt{7}} \cos y-\cos 2 y) \cdot$ If the answer is not an integer, round it to the nearest integer.
Answer: -19. Instructions. Exact answer: $2 \sqrt{7}-24$.