#include using namespace std; namespace { typedef double real; typedef long long ll; template ostream& operator<<(ostream& os, const vector& vs) { if (vs.empty()) return os << "[]"; auto i = vs.begin(); os << "[" << *i; for (++i; i != vs.end(); ++i) os << " " << *i; return os << "]"; } template istream& operator>>(istream& is, vector& vs) { for (auto it = vs.begin(); it != vs.end(); it++) is >> *it; return is; } void input() { } void solve() { int lb = 10, ub = int(1e9) + 1; while (true) { int mid = lb + (ub - lb) / 2; cout << "? " << mid << endl; int y; cin >> y; if (y < 0) { ub = mid; lb = max(0, lb - 1); } else if (y == 0) { cout << "! " << max(0, mid - 1) << endl; return; } else { assert(y > 0); lb = mid; } } } } int main() { input(); solve(); return 0; }