def main():
    N = int(input())
    C = tuple(map(int, input().split()))

    cnt = 0
    for i in C:
        if i >= 2:
            cnt += 1

    sumc = sum(C)
    maxc = max(C)
    if maxc == 1:
        if sumc % 2:
            ans = 'A'
        else:
            ans = 'B'
    elif maxc == 2:
        if cnt == 1:
            ans = 'A'
        else:
            ans = 'B'
    else:
        ans = 'B'

    print(ans)

main()