#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;
		//printf("l=%lld r=%lld m=%lld\n",l,r,m);
		cout<<"? "<<m<<endl;
		string res;
		getline(cin,res);
		
		if(res=="1") l=m;
		else r=m-1;
	}

	bool br;
	string res;	
	cout<<"? "<<r<<endl;
	getline(cin,res);	
	if(res=="1") br=true;
	else br=false;	
	
	if(br) cout<<"! "<<r<<endl;
	else cout<<"! "<<l<<endl;
	
	return 0;
}