N = int(input())
C = list(map(int, input().split()))
two = 0

for C_i in C:
    if C_i == 2:
        two += 1
        
    if C_i >= 3:
        print('B')
        exit()

if two >= 2:
    print('B')
    exit()

if (two == 1 and N % 2 == 0) or (two == 0 and N % 2 == 1):
    print('A')
else:
    print('B')