#include <iostream>
using namespace std;

int main(){
    int ac = 0;
    int wa = 1000000000;
    while(wa-ac > 1){
        int mid = (wa+ac)/2;
        cout << "? " << mid << endl;
        int res;
        cin >> res;
        if(res == 1) ac = mid;
        else wa = mid;
    }

    cout << "! " << ac << endl;
    return 0;
}