n = int(input())
C = list(map(int, input().split()))
c1 = 0
cx = 0
for c in C:
    if c == 1:
        c1 += 1
    if c > 2:
        cx += 1
if cx == 0:
    if c1%2 == 1:
        print('A')
    else:
        print('B')
else:
    print('B')