样例输入 #1
样例输出 #1
样例说明
INPUT DETAILS:
There are seven cows and they are facing backward, backward, forward, backward, forward, backward, and backward, respectively.
OUTPUT DETAILS:
For , the machine must be operated three times: turn cows ,, and finally :
B > F F F
B > F F F
F > B > F F
B B > F F
F F > B > F
B B B > F
B B B > F