#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <queue>
#include <cstdio>
#include <ctime>
#include <assert.h>
#include <chrono>
#include <random>
#include <numeric>
#include <set>
using namespace std;
typedef long long int ll;
typedef unsigned long long ull;


int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    ll l=1,r=1e9+1;
    while(r-l>1){
        ll mid=(l+r)/2;
        cout << "? " << mid << endl;
        int k; cin >> k;
        if(k)l=mid;
        else r=mid; 
    }
    cout << "! " << l << endl;
}