OJ Board

I am confused with the sample input given in the problem. Can you please explain me the input. What does 6 in the first line refers to? What are the slept areas initially? There are only 6 areas mentioned: A, B, C, D, F and H. What about remaining 5 areas.


6
11
HAB
AB
AC
AH
BD
BC
BF
CD
CF
CH
DF ...