#include <iostream>
#include <vector>
using namespace std;
struct SieveEratos{
  vector<int> t;
  SieveEratos(int n):t(n+1,true){
    t[0] = t[1] = 1;
    for(int i = 2; n >= i; i++){
      if(t[i]){
        for(int j = i+i; n >= j; j+=i){
          t[j] = 0;
        }
      }
    }
  }
  bool operator[](int x){return t[x];}
};

int main(){
  int n;cin>>n;
  SieveEratos SE(n);
  vector<int> p;
  for(int i = 2; n >= i; i++){
    if(SE[i])p.push_back(i);
  }
  int ans = 1;
  for(int i = 0; p.size() > i; i++){
    int nw = 1;
    while(n >= p[i]*nw){
      nw *= p[i];
    }
    cout << "? " << nw << endl;
    int t;
    cin>>t;
    if(t == -1){
      cout << 1/0 << endl;
    }
    ans *= t;
  }
  cout << ans << endl;
}