#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>
#include <numeric>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
//constexpr long long MAX = 5100000;
constexpr long long INF = 1LL << 60;
constexpr int inf = 1000000007;
constexpr long long mod = 1000000007LL;
//constexpr long long mod = 998244353LL;
const long double PI = acos((long double)(-1));

using namespace std;
typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;

int cnt = 0;
int ask(int X) {
    cout << "? " << X << endl;
    int res; cin >> res;
    if (res == 0) { cout << "! " << X + cnt << endl; exit(0); }
    cnt++;
    return res;
}
int main()
{
    /*
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    */
    int lf = 0;
    int rg = inf - 6;
    while (rg - lf > 1) {

        int mid = (lf + rg) >> 1;
        int r = ask(mid);
        if (r == 1) lf = mid + 1, rg = max(1, rg - 1);
        else rg = max(1, mid - 1), lf = max(0, lf - 1);

    }
    while(cnt < 95) ask(max(lf - 30,0));
    return 0;
}