#include #define rep(i,a,b) for(int i=a;i=b;i--) #define fore(i,a) for(auto &i:a) #define all(x) (x).begin(),(x).end() //#pragma GCC optimize ("-O3") using namespace std; void _main(); int main() { cin.tie(0); ios::sync_with_stdio(false); _main(); } typedef long long ll; const int inf = INT_MAX / 2; const ll infl = 1LL << 60; templatebool chmax(T& a, const T& b) { if (a < b) { a = b; return 1; } return 0; } templatebool chmin(T& a, const T& b) { if (b < a) { a = b; return 1; } return 0; } //--------------------------------------------------------------------------------------------------- /*---------------------------------------------------------------------------------------------------             ∧_∧       ∧_∧  (´<_` )  Welcome to My Coding Space!      ( ´_ゝ`) /  ⌒i @hamayanhamayan0     /   \    | |     /   / ̄ ̄ ̄ ̄/  |   __(__ニつ/  _/ .| .|____      \/____/ (u ⊃ ---------------------------------------------------------------------------------------------------*/ //--------------------------------------------------------------------------------------------------- bool ask(int y) { printf("? %d\n", y); fflush(stdout); int res; cin >> res; return res == 1; } void answer(int y) { printf("! %d \n", y); fflush(stdout); } //--------------------------------------------------------------------------------------------------- void _main() { int ok = 1, ng = 1e9 + 1; while (ok + 1 != ng) { int md = (ok + ng) / 2; if (ask(md)) ok = md; else ng = md; } cout << ok << endl; }