#include<sstream>
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
#include<bitset>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())
#define indexOf(v,x) (find(all(v),x)-v.begin())




int main(){
	int lb=0,ub=1000000000+1;
	while(ub-lb>1){
		int mid=(lb+ub)/2;
		cout<<"? "<<mid<<endl;
		int q;
		cin>>q;
		if(q==1)lb=mid;
		else ub=mid;
	}
	cout<<"! "<<lb<<endl;
	return 0;
}