import sys
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())


n = ii()
ans = list(range(1, n + 1))
import random
for _ in range(600):
    now = random.choice(ans[:max(1, len(ans) // 2)])
    print('?', now, flush = True)
    s = ii()
    if s == -1:
        exit()
    ans2 = []
    for v in ans:
        if v % s == 0:
            ans2.append(v)
    ans = ans2

print('!', ans.pop())