#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; i++)
using namespace std;

typedef long long ll;

int main() {
    string s;
    int ok = 0, ng = 1000, D = -1;
    while (ok + 1 < ng) {
        int x = (ok + ng) / 2;
        if (D != -1 && x % D == 0) {
            x++;
            if (x == ng) break;
        }
        cout << "? " << x << "\n";
        cin >> s;
        if (s == "safe") {
            ok = x;
            continue;
        }
        cout << "? " << x + 1 << "\n";
        cin >> s;
        if (s == "out") {
            ng = x;
        } else {
            ok = x + 1;
        }
    }
    cout << "! " << ok << "\n";
}