//
// Created by Owner on 2015/08/01.
//

#include <bits/stdc++.h>

using namespace std;

int cnt = 0;

int que(int num){
    cout << "? "  << num << endl;
    int rtn;
    cin >> rtn;
    cnt++;
    return rtn;
}

int main() {
    int max_num, min_num;
    max_num = 1000000000;
    min_num = 10;
    int ans;
    while ((max_num - min_num) > 1) {
        if ((cnt % 10) == 0) {
            ans = que(10);
            if (ans != 1) {
                if (ans == -1) {
                    while (true) {
                        ans = que(0);
                        if (ans == 0) {
                            break;
                        }
                    }
                }
                min_num = 0;
                break;
            }
        } else {
            int num = (max_num + min_num - cnt * 2) / 2;
            ans = que(num);
            if (ans == 0) {
                min_num = num;
                break;
            }
            if (ans == 1) {
                min_num = num + 1;
            } else {
                max_num = num;
            }
        }
    }

    cout << "! " << min_num + cnt + 1 << endl;

    return 0;
}