#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <cstring>

typedef long long ll;
using namespace std;

#define mod 1000003
#define INF 1000000000
#define LLINF 2000000000000000000LL

#define SIZE 100

int ask(int Y){
    cout << "? " << Y << endl;
    int res;
    cin >> res;
    return res;
}

void ans(int Y){
    cout << "! " << Y << endl;
    return;
}

int main(){
    int res;
    
    int l=10,r=1000000000,mid;
    
    if(ask(31)==-1){
        
        for(int i=0;;i++){
            if(ask(0)==0){
                ans(i);
            }
        }
        
    }
    
    for(int i=1;i<=30;i++){
        
        mid = (l+r)/2;
        
        int q = ask(mid-i);
        
        if(q==1){
            l = mid+1;
        }else if(q==-1){
            r = mid;
        }else{
            ans(mid);
            return 0;
        }
        
    }
    
    return 0;
}