#include <algorithm>
#include <functional>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <vector>
#include <list>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <bitset>
#include <climits>

#define all(c) (c).begin(), (c).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define pb(e) push_back(e)
#define mp(a, b) make_pair(a, b)
#define fr first
#define sc second

const int INF=100000000;
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
using namespace std;
typedef pair<int ,int > P;
typedef long long ll;

int main() {
    ll lb=-1,ub=1e9;
    while(ub-lb>1) {
        //cout << "debug: " << lb << ", " << ub <<endl;
        ll mid=(lb+ub)/2;
        cout << "? " << mid << endl;
        int t;
        cin>>t;
        if(t==0) ub=mid;
        else lb=mid;
    }

    cout << "! " << lb << endl;
    return 0;
}