n = int(input())
C = list(map(int, input().split()))
c1 = 0
c2 = 0
total = 0
for c in C:
    if c == 1:
        c1 += 1
    if c == 2:
        c2 += 1
    if c > 0:
        total += 1
if c2 == 0:
    if c1 == total and c1%2 == 1:
        print('A')
    else:
        print('B')
else:
    if c2 == 1 and c1 == total-1 and c1%2 == 1:
        print('A')
    else:
        print('B')