N = int(input())
boxes = [int(x) for x in input().split()]

n1 = 0
n2 = 0
for box in boxes:
    if box == 1:
        n1 += 1
    else:
        n2 += 1

if n1%2==1 and n2 <= 1:
    print('A')
else:
    print('B')