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

Counter = [0, 0, 0]
for i in range(n):
    if C[i] == 0:
        continue
    elif C[i] == 1:
        Counter[0] += 1
    elif C[i] == 2:
        Counter[1] += 1
    else:
        Counter[2] += 1
if Counter[2] > 0:
    print("B")
elif Counter[1] <= 1 and Counter[0] % 2 == 1:
    print("A")
else:
    print("B")