#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  int l = 1, r = 1e9 + 7;
  while (r - l > 1) {
    int mid = (l + r) / 2;
    cout << "? " << mid << endl;
    int t;
    cin >> t;
    (t ? l : r) = mid;
  }
  cout << "! " << l << endl;
  return 0;
}