#include <bits/stdc++.h>

using namespace std;

int main() {
    int max_num, min_num;
    max_num = 1000000000;
    min_num = 10;
    int cnt = 0;
    int ans;
    while ((max_num - min_num) > 1) {
        if ((cnt % 10) == 0) {
            cout << "? 10" << endl;
            cin >> ans;
            cnt++;
            if (ans != 1) {
                if (ans == -1) {
                    while (true) {
                        cout << "? 0" << endl;
                        cin >> ans;
                        if (ans == 0) {
                            break;
                        }
                        cnt++;
                    }
                }
                min_num = 0;
                break;
            }
        }
        int num = (max_num + min_num) / 2;
        cout << "? " << num << endl;
        cin >> ans;
        if(ans == 0){
            min_num = num;
            break;
        }
        if(ans == 1){
            min_num = num + 1;
        }else{
            max_num = num;
        }
        max_num--;
        min_num--;
        min_num = (min_num == 0) ? 0 : min_num - 1;
        cnt++;
    }
    cout << "! " << min_num + cnt << endl;

    return 0;
}