#include <bits/stdc++.h>

using namespace std;

long long binarySearch(function<bool(long long)> func, long long include, long long exclude) {
  while (abs(exclude - include) > 1) {
    long long middle = (include + exclude) / 2;
    (func(middle) ? include : exclude) = middle;
  }
  return include;
}

int main() {
  int cnt = 0;
  auto f = [&](int m){
    cout << "? " << m - cnt << endl;
    ++cnt;
    int res;
    cin >> res;
    return res >= 0;
  };
  cout << "! " << binarySearch(f, 10, f(100) ? 1e9 + 1 : 101) << endl;
}