N = int(input())
A2 = list(map(int,input().split()))
A = []
for a in A2:
    if a > 0:
        A.append(a)
N = len(A)

if N == 0:
    print("B")
elif max(A) > 2:
    print("B")
elif N - A.count(1) > 1:
    print("B")
elif max(A) == 2:
    if N % 2 == 0:
        print("A")
    else:
        print("B")
else:
    if N % 2 == 0:
        print("B")
    else:
        print("A")