n = int(input())

G = [0, 0, 1, 2, 2]
for x in range(5, n + 1):
    seen = set()
    if x % 2 == 0:
        g = 0
    else:
        g = G[x // 2] ^ G[x // 2 + 1]
    seen.add(g)
    if x % 3 == 1:
        g = G[x // 3 + 1]
    else:
        g = G[x // 3]
    seen.add(g)
    g = 0
    while g in seen:
        g += 1
    G.append(g)
if G[n] == 0:
    print("B")
else:
    print("A")