N = int(input())
lsC = list(map(int,input().split()))
B = len(lsC)-lsC.count(0)
if B % 2== 1 and lsC.count(1)==B:
    print('A')
elif B % 2==0 and lsC.count(1)==B-1 and lsC.count(2) == 1:
    print('A')
else:
    print('B')