N = int(input())
gr = [-1]*(N+1)
gr[1] = 0
for i in range(2, N+1):
    S = {gr[i//2] ^ gr[N-i//2]}
    if i > 2:
        if i % 3 == 1:
            S.add(gr[i//3+1])
        else:
            S.add(gr[i//3])
    for j in range(3):
        if j not in S:
            gr[i] = j
            break

print('A' if gr[N] else 'B')