#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <sstream>
#include <functional>
#include <map>
#include <string>
#include <cstring>
#include <vector>
#include <queue>
#include <stack>
#include <deque>
#include <set>
#include <list>
#include <numeric>
using namespace std;
const double PI = 3.14159265358979323846;
const double EPS = 1e-12;
const int INF = 1<<25;
typedef pair<int,int> P;
typedef long long ll;
typedef unsigned long long ull;


int main(){
	ll lb = 1, ub = 1e9+1;
	while(ub-lb>1){
		ll md = (lb+ub)/2;
		cout<<"? "<<md<<endl;
		int r;
		cin>>r;
		if(r) lb = md;
		else ub = md;
	}
	cout<<"! "<<lb<<endl;
	return 0;
}