N = int(input())
A = list(map(int,input().split()))
C = {0:0,1:0,2:0}
for i in range(N):
    C[A[i]] = C.get(A[i],0)+1
N -= C[0]
if N%2==0 and C[1]==N-1 and C[2]==1 or C[1]==N and N%2==1:
    print("A")
else:
    print("B")