n = int(input())
c = list(map(int, input().split()))
ones = sum(1 for x in c if x == 1)
has_large = any(x > 1 for x in c)

if has_large:
    print("A" if ones % 2 == 1 else "B")
else:
    print("A" if ones % 2 == 1 else "B")