#include using namespace std; #define FOR(i,a,b) for(int i=(a);i<(b);i++) #define REP(i,n) FOR(i,0,n) #define ALL(v) (v).begin(),(v).end() template inline bool chmax(A &a, B b) { if (a inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; } typedef unsigned long long ull; typedef long long ll; typedef pair pii; typedef pair pll; typedef pair P; const ll INF = 1ll<<29; const ll MOD = 1000000007; const double EPS = 1e-10; int main() { int l = 0, r = 1e9; while (r - l > 1) { int m = (l + r) / 2; printf("? %d\n", m); fflush(stdout); int res; scanf("%d", &res); if (res) l = m; else r = m; } printf("! %d\n", l); return 0; }