#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using mint = atcoder::modint998244353;
using maxt = atcoder::modint1000000007;
vector<ll> Era(int N) {
  vector<ll> ans(0, 0);
  vector<bool> isprime(N + 1, true);
  isprime.at(1) = false;
  for(int i = 1; i <= N; i++) {
    if(isprime.at(i)) {
      ans.push_back(i);
      for(int j = 2 * i; j <= N; j += i) {
        isprime.at(j) = false;
      }
    }
  }
  return ans;
}
ll POW(ll a, int N) {
  if(N == 1) {
    return a;
  }
  ll ans = POW(a, N / 2) * POW(a, N / 2);
  if(N % 2 == 1) {
    ans *= a;
  }
  return ans;
}

//ライブラリここまで

int main() {
  int l = 1, r = 1000000001, c = 0;
  while(r - l > 1) {
    c = (l + r) / 2;
    cout << "? " << c << endl;
    int ans;
    cin >> ans;
    if(ans) {
      l = c;
    }
    else {
      r = c;
    }
  }
  cout << "! " << l << endl;
}