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

count_k = 0  # number of boxes with exactly 1 candy
count_m = 0  # number of boxes with more than 1 candy

for c in candies:
    if c == 1:
        count_k += 1
    elif c > 1:
        count_m += 1

if count_m == 0:
    # All boxes are 0 or 1; only 1's matter
    if count_k % 2 == 1:
        print("A")
    else:
        print("B")
else:
    # At least one box with more than 1; parity of count_k determines outcome
    if count_k % 2 == 1:
        print("A")
    else:
        print("B")