#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#include "../../debug.h"
#else
#define dbg(...) 787788
#endif

void solve() {
    // ask y
    // 1 -> x < y
    int l = 1, r = 1e9 + 1;
    while (r - l > 1) {
        int m = (l + r) >> 1;
        cout << "? " << m << endl;
        int res;
        cin >> res;
        assert(res == 0 || res == 1);
        if (res == 1) {
            r = m;
        } else {
            l = m;
        }
    }
    cout << "! " << l << endl;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

#ifdef LOCAL
#include <filesystem>
    int tests = 0;
    for (const auto &entry : std::filesystem::directory_iterator("tests")) {
        const string path = entry.path();
        int len = path.size();
        if (len < 3 || path.substr(len - 3) != ".in") {
            continue;
        }
        if (path != "tests/1.in") {
            // continue;
        }
        std::cout << "\u001b[31m" << path << "\u001b[0m" << std::endl;

        std::ifstream f(path);
        if (f.is_open())
            std::cout << "input:\n"
                      << f.rdbuf() << "\n\noutput:\n";

        freopen(path.c_str(), "r", stdin);
        solve();
        cout << "\n\n";
        tests += 1;
    }
    if (tests == 0) {
        solve();
    }
#else
    solve();
#endif
}