#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <iostream>
#include <vector>
#include <string>
#include <sstream>
#include <algorithm>
#include <utility>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <deque>
#include <functional>

using namespace std;

#define fst first
#define scd second
#define PB push_back
#define MP make_pair
#define size(a) ((int)a.size())
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define omajinai ios::sync_with_stdio(false);cin.tie(0)

typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> pii;
typedef vector<pii> vpii;

template<typename T>T& max(T&a,T&b){if(a>=b)return a;return b;}
template<typename T>T& min(T&a,T&b){if(a<b)return a;return b;}
template<typename T>bool chmax(T&a,T b){if(a<b){a=b;return true;}return false;}
template<typename T>bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;}
template<typename T>T get(){T a;cin>>a;return a;}
template<typename T>T rev(T a){reverse(all(a));return a;}
template<typename T>vector<T>&sort(vector<T>&a){sort(all(a));return a;}

const int inf = 1e9;
const ll linf = 3e18;
const double eps = 1e-9;

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

void answer(int x)
{
    cout << "! " << x << endl;
}

signed main()
{
    if (ask(101) == -1) { // 99
        int a = 9;
        for (int i = 1; i <= 99; ++i) {
            if (ask(a) == 0) {
                answer(a + i);
                return 0;
            }
        }
    }

    int lb = 0, ub = 1e9;

    int counter = 0;

    for (int i = 1; i <= 30; ++i) {
        int mid = (lb + ub) / 2;

        int res = ask(mid);

        if (res == 0) {
            answer(mid + i);
            return 0;
        } else if (res == -1) {
            ub = mid;
            lb -= 2;
        } else if (res == 1) {
            lb = mid - 2;
        }

        lb = max(lb, 0);
    }

    for (int i = 1; i <= 30; ++i) {
        cout << "? " << lb << endl;
        int res; cin >> res;
        if (res == 0) {
            answer(lb + 30 + i);
            return 0;
        }
    }
}