#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
//using mint = modint1000000007;
//using mint = modint;//mint::set_mod(MOD);

const long long MOD = 998244353;
//const long long MOD = 1000000007;

#include <bits/stdc++.h>
#define rep(i,a,b) for(ll i=(ll)(a);i<(ll)(b);i++)
#define repeq(i,a,b) for(ll i=(ll)(a);i<=(ll)(b);i++)
#define repreq(i,a,b) for(ll i=(ll)(a);i>=(ll)(b);i--)
#define each(a,b) for(auto& (a):(b))
#define endl '\n'
#define cYes cout<<"Yes"<<endl
#define cNo cout<<"No"<<endl
#define sortr(v) sort(v,greater<>())
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define tget(a,b) get<b>(a)
#define FI first
#define SE second
#define ALL(v) (v).begin(),(v).end()
#define INFLL 3000000000000000100LL
#define INF 1000000100
#define PI acos(-1.0L)
#define TAU (PI*2.0L)

using namespace std;

typedef long long ll;
typedef pair<ll,ll> Pll;
typedef tuple<ll,ll,ll> Tlll;
typedef vector<int> Vi;
typedef vector<Vi> VVi;
typedef vector<ll> Vl;
typedef vector<Vl> VVl;
typedef vector<VVl> VVVl;
typedef vector<Tlll> VTlll;
typedef vector<mint> Vm;
typedef vector<Vm> VVm;
typedef vector<string> Vs;
typedef vector<double> Vd;
typedef vector<char> Vc;
typedef vector<bool> Vb;
typedef vector<Pll> VPll;
typedef priority_queue<ll> PQl;
typedef priority_queue<ll,vector<ll>,greater<ll>> PQlr;

/* print */
template <typename T>
ostream& operator<<(ostream& os,const vector<T> &V){
int N=V.size();if(N==0){os<<endl;return os;}
rep(i,0,N-1){os<<V[i]<<' ';}os<<V[N-1]<<endl;return os;}
template <typename T>
ostream& operator<<(ostream& os,const vector<vector<T>> &V){
int N=V.size();rep(i,0,N)os<<V[i];return os;}
template <typename T,typename S>
ostream& operator<<(ostream&os,pair<T,S>const&P){os<<P.FI<<' '<<P.SE;return os;}
ostream& operator<<(ostream&os,mint const&M){os<<M.val();return os;}

/* useful */
template<typename T>void Vin(vector<T> &v){int n=v.size();rep(i,0,n)cin>>v[i];}
template<typename T>int SMALLER(vector<T> &a,T x){
return lower_bound(a.begin(),a.end(),x)-a.begin();}
template<typename T>int orSMALLER(vector<T> &a,T x){
return upper_bound(a.begin(),a.end(),x)-a.begin();}
template<typename T>int BIGGER(vector<T>&a,T x){return a.size()-orSMALLER(a,x);}
template<typename T>int orBIGGER(vector<T>&a,T x){return a.size()-SMALLER(a,x);}
template<typename T>int COUNT(vector<T> &a,T x){
return upper_bound(ALL(a),x)-lower_bound(ALL(a),x);}
template<typename T>bool chmax(T &a,T b) {if(a<b){a=b;return 1;}return 0;}
template<typename T>bool chmin(T &a,T b) {if(a>b){a=b;return 1;}return 0;}
template<typename T>void press(T &v){v.erase(unique(ALL(v)),v.end());}
template<typename T>vector<int> zip(vector<T> b){pair<T,int> p[b.size()+10];
int a=b.size();vector<int> l(a);for(int i=0;i<a;i++) p[i]=mp(b[i],i);
sort(p,p+a);int w=0;for(int i=0;i<a;i++){if(i&&p[i].first!=p[i-1].first)w++;
l[p[i].second]=w;}return l;}
template<typename T>vector<T> vis(vector<T> &v){
vector<T> S(v.size()+1);rep(i,1,S.size())S[i]+=v[i-1]+S[i-1];return S;}

ll dem(ll a,ll b){return((a+b-1)/(b));}
ll dtoll(double d,int g){return round(d*pow(10,g));}

const double EPS = 1e-10;

void init(){
cin.tie(0);cout.tie(0);ios::sync_with_stdio(0);cout<<fixed<<setprecision(12);}

/********************************** START **********************************/



void sol() {
  int n;cin >> n;
  if(n > 600) return;
  int ans = 0;
  repeq(i,1,n) {
    cout << "? " << i << endl;
    fflush(stdout);
    int qw;cin >> qw;
    if(i == qw) {
      chmax(ans, qw);
    }
  }
  cout << "! " << ans << endl;
  return;
}

int main() {
  init();
  int q = 1;
  //cin >> q;
  while(q--) sol();
  return 0;
}