#include <iostream>
#include <string>
#include <vector>
#include <cmath>
#include <algorithm>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <functional>
#include <set>
#include <sstream>
#include <map>
#include <queue>
#include <stack>

using namespace std;


int main()
{

    long long l=1,r=1000000000;
    
    while(l+1!=r){
        //cout<<"l="<<l<<" r="<<r<<endl;
        long long m=(l+r)/2;
        cout<<"? "<<m<<endl;
        int res;
        cin>>res;
        
        if(res) l=m;
        else r=m-1;
    }

    cout<<"! "<<l<<endl;

    return 0;
}