N = int(input())
C = list(map(int,input().split()))
one = 0
two = 0
more = False 
for i in range(N):
    if C[i]==1:
        one+=1
    if C[i]==2:
        two+=1
    if C[i]>2:
        more=True
if not more and two<=1:
    if (one+two*2)%2==1:
        print('A')
    else:
        print('B')
else:
    print('B')