#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    int ok = 1, ng = 1000000001, mid;
    while(ok + 1 < ng){
        mid = (ok + ng) / 2;
        cout << "? " << mid << endl;
        int v;
        cin >> v;
        if(v) ok = mid;
        else ng = mid;
    }
    cout << "! " << ok << endl;
}