n = int(input())
a = [int(a) for a in input().split()]

if max(a) == 1 and a.count(1)%2 == 1:
    print("A")
elif max(a) == 2 and a.count(2) == 1 and a.count(1)%2 == 1:
    print("A")
else:
    print("B")