#include <bits/stdc++.h>
using namespace std;
using ll = long long int;
int main(){
    ll N;
    cin >> N;
    for(ll i = N;i >= 1;i--){
        cout << "? " << i << endl;
        ll a;
        cin >> a;
        if(a == i){
            cout << "! " << a << endl;
            return 0;
        }
    }
}