N = int(input())
C = list(map(int, input().split()))
num2 = 0
num1 = 0
for n in C:
    if n >= 3:
        print('B')
        exit()
    elif n == 2:
        num2 += 1
    elif n == 1:
        num1 += 1
if num2 >= 2:
    print('B')
else:
    print('A' if num1 % 2 == 1 else 'B')