B 2a

B 2aB 2aB 2aB 2a
B 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2a
B 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2a
B 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2a
B 2aB 2aB 2aB 2aB 2aB 2aB 2aB 2a