#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    int l = 10, r = 1001001001;
    int loop = 0;
    while(l + 1 < r){
        loop++;
        if(loop % 2 == 1){
            cout << "? 1" << endl;
            fflush(stdout);
            int x;
            cin >> x;
            if(x == 0){
                cout << "! " << loop << endl;
                return 0;
            }else if(x == -1){
                cout << "! " << loop - 1 << endl;
                return 0;
            }else{
                l--;
                l = max(0,l);
                r--;
            }
        }else{
            int m = (l+r)/2;
            cout << "? " << m << endl;
            fflush(stdout);
            int x;
            cin >> x;
            if(x == 0){
                cout << "! " << max(0,m-1+loop) << endl;
                fflush(stdout);
                return 0;
            }
            if(x == 1){
                l = m;
            }else{
                r = m;
            }
            l--;
            l = max(0,l);
            r--;
        }     
    }
    cout << "! " << l + loop<< endl;
    fflush(stdout);
    return 0;
}