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

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

	return 0;
}