#include <bits/stdc++.h>
using namespace std;
int ask(int y){
	cout<<"? "<<y<<endl;
	int ans;
	cin>>ans;
	return ans;
}
int main(){
	int ple=100;
	int left=1e9,right=10;
	int cnt=0;
	for(;cnt<10;cnt++){
		int ans=ask((ple+right)/2);
		if(ans==0){
			printf("!%d\n",(ple+right)/2+cnt);
			return 0;
		}
		else if(ans==1)	right=(ple+right)/2;
		else 	ple=(ple+right)/2;
	}
	right=10;
	for(;cnt<100;cnt++){
		int ans=ask((left+right)/2);
		if(ans==0){
			printf("!%d\n",(left+right)/2+cnt);
			return 0;
		}
		else if(ans==1)	right=(left+right)/2;
		else 	left=(left+right)/2;
	}
}