def Eratosthenes(N):
  is_prime = [1 for i in range(N+1)]
  is_prime[0] = is_prime[1] = 0
  P = []
  for p in range(2,N+1):
    if is_prime[p] == 0:
      continue
    P.append(p)
    for d in range(2,N//p+1):
      q = p*d
      is_prime[q] = 0
  return P

def ques(y):
  print('?',y)

N = int(input())

P = Eratosthenes(N)
D = [0 for i in range(len(P))]

for i in range(len(P)):
  p = P[i]
  for d in range(1,20):
    n = pow(p,d)
    if n > N:
      break
    ques(n)
    z = int(input())
    if n == z:
      D[i] = d
    else:
      break

ans = 1
for i in range(len(P)):
  p,d = P[i],D[i]
  ans *= pow(p,d)
print(ans)