/* Author : Mohd Athar */
#include<bits/stdc++.h>
using namespace std;
#define ll long long
int ans,n;
bool query(int mid){
    int x,y;
    if(mid < n){
        cout<<"? "<<mid<<endl;
        cin>>x;
        cout<<"? "<<mid + 1<<endl;
        cin>>y;
    }
    else{
        cout<<"? "<<mid<<endl;
        cin>>x;
        y = 1000005;
    }

    return (x > y);
}
int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

  
    cin>>n;

    int s = 1;
    int e = n;

    if(n == 1){
        cout<<"! "<<n<<endl;
        return 0;
    }

    while(s < e){
        int mid = (s+e)/2;
        ans = mid;
        if(query(mid)){
            s = mid+1;
            if(s == e)
                ans = s;
        }
        else{
            e = mid;
        }
    }
    cout<<"! "<<ans<<endl;

    return 0;
}