#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define llong long long

int main() {
    int ulim = 1e9;
    int llim = 1;
    while(ulim > llim) {
        int mid = (ulim + llim + 1) / 2;
        cout << "? " << mid << endl;
        int i;
        cin >> i;
        if(i == 1) llim = mid;
        else ulim = mid-1;
    }
    cout << "! " << ulim << endl;
    return 0;
}