#include <bits/stdc++.h> #define rep(i, a) for (int i = 0; i < (a); i++) #define rep2(i, a, b) for (int i = (a); i < (b); i++) #define repr(i, a) for (int i = (a) - 1; i >= 0; i--) #define repr2(i, a, b) for (int i = (b) - 1; i >= (a); i--) #define itall(a) a.begin(), a.end() using namespace std; typedef long long ll; const ll inf = 1e9; const ll mod = 1e9 + 7; const double pi = acos(-1); const double eps = 1e-8; template<typename T> inline T sq(T a) { return a * a; } template<typename T> inline T cb(T a) { return a * a * a; } template<typename T> inline bool umin(T &a, const T &b) { return b < a && (a = b, true); } template<typename T> inline bool umax(T &a, const T &b) { return a < b && (a = b, true); } int get(int x) { cout << "? " << x << endl; int res; cin >> res; return res; } int main() { int l = 0, r = 1e9 + 1; int ans = 0; for (int i = 0;; i++) { int m = (l + r) / 2; int g = get(m); if (g == 0) { ans = m + i; break; } else if (g > 0) { l = m; } else { r = m; } } cout << ans << endl; }