#include #define For(i, a, b) for (int(i) = (int)(a); (i) < (int)(b); ++(i)) #define rFor(i, a, b) for (int(i) = (int)(a)-1; (i) >= (int)(b); --(i)) #define rep(i, n) For((i), 0, (n)) #define rrep(i, n) rFor((i), (n), 0) #define fi first #define se second using namespace std; typedef long long lint; typedef unsigned long long ulint; typedef pair pii; typedef pair pll; template bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; } template bool chmin(T &a, const T &b) { if (a > b) { a = b; return true; } return false; } template T div_floor(T a, T b) { if (b < 0) a *= -1, b *= -1; return a >= 0 ? a / b : (a + 1) / b - 1; } template T div_ceil(T a, T b) { if (b < 0) a *= -1, b *= -1; return a > 0 ? (a - 1) / b + 1 : a / b; } constexpr lint mod = 1000000007; constexpr lint INF = mod * mod; constexpr int MAX = 200010; string interact(int x) { cout << "? " << x << endl; string s; cin >> s; return s; } int main() { int low = 0, high = 1001; while (high - low > 1) { int mid = (high + low) / 2; if (interact(mid) == "safe") low = mid; else { if (interact(mid + 1) == "safe") low = mid + 1; else high = mid; } } cout << "! " << low << endl; }