#define _USE_MATH_DEFINES
 
#include <iostream>
#include <iomanip>
 
#include <algorithm>
#include <cmath>
 
#include <string>
//#include <array>
#include <list>
#include <queue>
#include <vector>
#include <complex>
#include <set>
#include <map>
 
/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)
#define P(p) cout<<(p)<<endl;
 
#define PII pair<int,int>
/////////
typedef long long LL;
typedef long double LD;
/////////
using namespace::std;
/////////

int main(void){
    std::cin.tie(0); 
    std::ios::sync_with_stdio(false);
    std::cout << std::fixed;//
    //cout << setprecision(10);//
	
	//1->10^9
	int Left = 1;
	int Right = (int)1e9;
	int mid;
	int res;
	while( Left < Right ){
		mid = (Right+Left)/2;
		cout<< "? "<<mid<<endl;
		cin>>res;
		if(res==1){
			Left = mid;
		}else{
			Right = mid-1;
		}
		if(Right-Left == 1){
			cout<<"? "<<Right<<endl;
			cin>>res;
			if(res==1){
				cout<<"! "<<Right<<endl;
				return 0;
			}else{
				cout<<"! "<<Left<<endl;
				return 0;
			}
		}
	}
	cout<<"! "<<Left<<endl;
    return 0;
}