N = int(input())
G = [0,0,1,2,2]
for x in range(5,N+1):
  S = set()
  if x % 2 == 0:
    g = 0
  else:
    g = G[x//2] ^ G[x//2 + 1]
  S.add(g)
  if x % 3 == 1:
    g = G[x//3 + 1]
  else:
    g = G[x//3]
  S.add(g)
  g = 0
  while g in S:
    g += 1
  G.append(g)
ans = 'A'
if G[N] == 0:
  ans = 'B'
print(ans)