B1 b2

B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2
B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2
B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2B1 b2