#if __INCLUDE_LEVEL__ == 0

#include __BASE_FILE__

void Solve() {
  int L = 1;
  int R = 1e6;
  int last = -100;
  OUT('?', last);
  while (L < R) {
    int M = midpoint(L, R);
    // [L, M], [M+1, R]
    int nxt = (2 * M + 1) - last;
    OUT('?', nxt);
    int res;
    IN(res);
    if (last < L) {
      if (res == 0) {
        R = M;
      } else {
        L = M + 1;
      }
    } else if (R < last) {
      if (res == 0) {
        L = M + 1;
      } else {
        R = M;
      }
    } else {
      assert(false);
    }
    last = nxt;
  }
  OUT('!', L);
}

int main() {
  ios::sync_with_stdio(false);

  Solve();
}

#elif __INCLUDE_LEVEL__ == 1

#include <bits/stdc++.h>

template <class T> concept MyRange = std::ranges::range<T> && !std::convertible_to<T, std::string_view>;
template <class T> concept MyTuple = std::__is_tuple_like<T>::value && !MyRange<T>;

namespace std {

istream& operator>>(istream& is, MyRange auto&& r) {
  for (auto&& e : r) is >> e;
  return is;
}
istream& operator>>(istream& is, MyTuple auto&& t) {
  apply([&](auto&... xs) { (is >> ... >> xs); }, t);
  return is;
}

ostream& operator<<(ostream& os, MyRange auto&& r) {
  auto sep = "";
  for (auto&& e : r) os << exchange(sep, " ") << e;
  return os;
}
ostream& operator<<(ostream& os, MyTuple auto&& t) {
  auto sep = "";
  apply([&](auto&... xs) { ((os << exchange(sep, " ") << xs), ...); }, t);
  return os;
}

}  // namespace std

using namespace std;

#define IN(...) (cin >> forward_as_tuple(__VA_ARGS__))
#define OUT(...) (cout << forward_as_tuple(__VA_ARGS__) << '\n')

#endif  // __INCLUDE_LEVEL__ == 1