#include <bits/stdc++.h>

using namespace std;

int query(int x) {
    cout << "? " << x << endl;
    fflush(stdout);

    int ans; cin >> ans;

    return ans;
}

void answer(int x) {
    cout << "! " << x << endl;
    fflush(stdout);
}

int main() {
    int n; cin >> n;

    for(int i = 1; i <= n; i++) {
        if(query(i) == 1) {
            answer(i);
            exit(0);
        }
    }
}