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

bwin_f = 0
two_f = 0
count = 0

for l_i in l:
    if l_i != 0:
        count += 1
    if l_i > 2:
        bwin_f += 1
    if l_i == 2:
        two_f += 1


if bwin_f == 0 and two_f == 1 and count % 2 == 0:
    print("A")
elif bwin_f == 0 and two_f == 0 and count % 2 == 1:
    print("A")
else:
    print("B")