def eratosthenes(n):
    res=[0]*(n+1)
    prime=set([])
    for i in range(2,n+1):
        if not res[i]:
            prime.add(i)
            for j in range(i,n+1,i):
                res[j]=1
    return sorted(list(prime))
N=int(input())
prime = eratosthenes(N)
ans = 1
cnt=0
for p in prime:
    y=1
    while cnt<600:
        cnt+=1
        y*=p
        print(f"? {y}", flush=True)
        s=int(input())
        if s<=1:break
        if s==y:continue
        ans *= y//p
        break
    if cnt>=600:break
print(f"! {ans}", flush=True)