#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
using namespace std;

using ll = long long;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    // int ans;
    // cin >> ans;
    int lb = 10, ub = 100, t = 0, x;
    while(ub - lb > 1){
        int mid = (lb + ub) / 2;
        cout << "? " << mid << endl;
        // cout << "ans:" << ans-- << endl;
        cin >> x;
        if(x == 0){
            cout << "! " << mid + t << endl;
            return 0;
        }
        if(x == 1)  lb = mid;
        else    ub = mid;
        ++t;
    }
    if(ub < 100){
        cout << "! " << lb + t - 1 << endl;
        return 0;
    }
    lb = 100, ub = 1e+9;
    while(ub - lb > 1){
        int mid = (lb + ub) / 2;
        cout << "? " << mid << endl;
        // cout << "ans:" << ans-- << endl;
        cin >> x;
        if(x == 0){
            cout << "! " << mid + t << endl;
            return 0;
        }
        if(x == 1)  lb = mid;
        else    ub = mid;
        ++t;
    }
    cout << "! " << lb + t - 1 << endl;

    return 0;
}