2
B 1
B -1
2
B 1
B -1
2
B 1
B -1
2
B 1
B -1
2
B 1
B -1
2
B 1
B -1
2
B 1
B -1
2
B 1
B -1
2
B 1
B -1
2
B 1
B -1