N = int(input())
C = list(map(int,input().split()))

one_count = 0
more_than_two_count = 0
for c in C:
    if c == 1:
        one_count += 1
    elif c >= 2:
        more_than_two_count += 1

if more_than_two_count >= 2:
    print("B")
elif more_than_two_count == 1:
    if one_count == 1:
        print("A")
    else:
        print("B")
else:
    if one_count % 2 == 1:
        print("A")
    else:
        print("B")