#include <bits/stdc++.h>

using namespace std;

int main() {
    int max_num = 1000000000;
    int min_num = 1;

    for (int i = 0; i < 100; i++) {
        int num = (max_num + min_num) / 2;
        cout << "? " << num << endl;

        int tmp;
        cin >> tmp;
        if (tmp == 1) {
            min_num = num;
        } else {
            max_num = num;
        }

        if ((max_num - min_num) <= 1) {
            break;
        }
    }
    cout << "! " << min_num << endl;

    return 0;
}