#include <iostream>
#include <cstdio>
#include <cmath>
#include <utility>
#include <algorithm>
#include <vector>
#include <cstring>

#define _P(x) printf(x);
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))

using namespace std;

typedef vector<int> vi;
typedef pair<int,int> ii;
typedef long long ll;



int main(){

int sec=0;
int l=10,r=1e9;
int rez;
int a;
cout<<"? 101"<<endl;
cin>>a;
if(a==-1)
r=100;
else if(a==0){
	cout<<"! "<<101<<endl;
	return 0;
}
else l=102;
sec++;
while(l<=r){
int mid=(l+r)/2-sec;
cout<<"? "<<mid<<endl;
cin>>a;
if(a==0){
rez=mid+sec;
break;
}
if(a==1){
l=mid+sec+1;
rez=mid+sec;	
}
if(a==-1)
r=mid+sec-1;
sec++;
}
cout<<"! "<<rez<<endl;
return 0;
}