#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)n;++i)
#define each(a, b) for(auto (a): (b))
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
#define pb push_back
#define show(x) cout<<#x<<" = "<<(x)<<endl
#define spair(p) cout<<#p<<": "<<p.fi<<" "<<p.se<<endl
#define svec(v) cout<<#v<<":";rep(kbrni,v.size())cout<<" "<<v[kbrni];cout<<endl
#define sset(s) cout<<#s<<":";each(kbrni,s)cout<<" "<<kbrni;cout<<endl
#define smap(m) cout<<#m<<":";each(kbrni,m)cout<<" {"<<kbrni.first<<":"<<kbrni.second<<"}";cout<<endl
using namespace std;

typedef pair<int,int>P;

const int MAX_N = 100005;

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int l=10,h=1000000001;
    cout << "? " << 1000 << endl;
    int cnt = 0;
    int fres;
    cin >> fres;
    if(fres == 0){
        cout << "! " << fres << endl;
    }else if(fres < 0){
        h=1000;
        while(1){
            cnt++;
            l--,h--;
            int mid = (l+h)/2;
            if(mid == l){
                cout << "! " << mid + cnt << endl;
                return 0;
            }
            cout << "? " << mid << endl;
            int res;
            cin >> res;
            if(res == 0){
                cout << "! " << mid + cnt << endl;
                return 0;
            }else if(res < 0){
                h=mid;
            }else{
                l=mid+1;
            }
        }
    }else{
        l=1001;
        while(1){
            cnt++;
            l--,h--;
            int mid = (l+h)/2;
            if(mid == l){
                cout << "! " << mid + cnt << endl;
                return 0;
            }
            cout << "? " << mid << endl;
            int res;
            cin >> res;
            if(res == 0){
                cout << "! " << mid + cnt << endl;
                return 0;
            }else if(res < 0){
                h=mid;
            }else{
                l=mid+1;
            }
        }
    }
    return 0;
}