#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() {
  auto f = [](int m){
    cout << "? " << m << endl;
    int res;
    cin >> res;
    return res;
  };
  cout << "! " << binarySearch(f, 1, 1e9 + 1) << endl;
}