#include <iostream>
#include <stdio.h>
#include <cmath>
using namespace std;

int main(){
    int l,r;
    l = 1; r = pow(10,9);

    char c;

    while(1){
        int mid = ceil((double)(l+r)/2);
        cout << '?' << ' ' << mid << endl;
        fflush(stdout);
        cin >> c;
        if(c == '1') l = mid;
        else r = mid-1;

        if(r - l == 1){
            cout << '?' << ' ' << r << endl;
            fflush(stdout);
            cin >> c;
            if(c == 1) cout << '!' << ' ' << r << endl;
            else cout << '!' << ' ' << l << endl;
            return 0;
        }

        if(r == l){
            cout << '!' << ' ' << r << endl;
            return 0;
        }
    }
}