#include <bits/stdc++.h>
using namespace std;

bool ask(int y){
	cout<<"? "<<y<<endl;
	int res;
	cin>>res;
	return res>=0;
}

int main(){
	int ct=1;
	int l,r;
	if(ask(138)){
		l=138,r=1e9+1;
	}else{
		l=10,r=138;
	}
	while(r-l>1){
		int mid=(l+r)/2;
		if(ask(mid-ct)){
			l=mid;
		}else{
			r=mid;
		}
		ct++;
	}
	cout<<"! "<<l<<endl;
}