N = int(input())
C = list(map(int,input().split()))
count = 0
count1 = 0
count2 = 0
for i in C:
    if i == 0:continue
    if i== 1:count1 += 1
    elif i == 2:count2 += 1
    else:count += 1
if count:print('B')
elif count2 == 1 and count1 % 2 == 0:
    print('A')
elif count2 == 0  and count1 % 2 == 0:
    print('A')
else:
    print('B')