#include<iostream>
#include<sstream>
#include<cstdio>
#include<cstring>
#include<string>
#include<vector>
#include<list>
#include<queue>
#include<utility>
#include <fstream>
#include<set>
#include<map>
#include<cctype>
#include<cmath>
#include<algorithm>
using namespace std;


#define RALL(x) (x).rbegin(),(x).rend()
#define ALL(x) (x).begin(),(x).end()
#define repp(i,n) for(int (i)=1;(i)<=(n);(i)++)
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define rev(i,n) for(int (i)=(n-1);(i)>=0;(i)--)
#define clr(a) memset((a), 0 ,sizeof(a))

typedef pair<int,int> P;
typedef vector<pair<int,string> > pii;
typedef map<string,int> mdi;


int main(void){
	long long a = 0, b = 2e9;
	while (b - a >= 2){
		long long mid = (a + b) / 2;
		cout << "? " << mid << endl;
		int res;
		cin >> res;
		if(res){
			a = mid;
		}
		else{
			b = mid;
		}
	}
	cout << "! " << a << endl;
	
	return 0;
}