def main():
    N = int(input())
    boxes = list(map(int, input().split()))
    no_candy_box_count = boxes.count(0)
    one_candy_box_count = boxes.count(1)
    two_candy_box_count = boxes.count(2)
    if no_candy_box_count == N:
        print("B")
    elif no_candy_box_count + one_candy_box_count == N and one_candy_box_count % 2 == 1:
        print("A")
    elif two_candy_box_count == 1 and one_candy_box_count % 2 == 1:
        print("A")
    else:
        print("B")

if __name__ == '__main__':
    main()