20
3
3
B B C C C C C C A A A A A A A A A A A A
B B C C C C C C A A A A A A A A A A A A
B B C C C C C C A A A A A A A A A A A A
B B C C C C C C A A A A A A A * A A A A
B B C C C C C C C A A A A A A A A A A A
B B C C C C C C C C A A A A A A A A A A
B B C C * C C C C C C A A A A A A A A A
B B B C C C C C C C C A A A A A A A A A
* B B B C C C C C C C A A A A A A A A A
B B B B C C C C C C C A A A A A A A A A
B B B B C C C C C C C A A A A A A A A A
B B B B C C C C C C C A A A A A A A A A
B B B B C C C C C C C A A A A A A A A A
B B B B C C C C C C C A A A A A A A A A
B B B B C C C C C C C A A A A A A A A A
B B B B C C C C C C C A A A A A A A A A
B B B B C C C C C C C A A A A A A A A A
B B B B C C C C C C C A A A A A A A A A
B B B B C C C C C C C A A A A A A A A A
B B B B C C C C C C C A A A A A A A A A