#include <algorithm>
#include <complex>
#include <iomanip>
#include <iostream>
#include <queue>
#include <set>
#include <vector>
#define rep(i, j, n) for (int i = (j); i < (n); ++i)
using namespace std;
using ll = long long;

int main() {
  string s, t;
  int l = -1, r = 1010;
  while (true) {
    int mid = (l + r) >> 1;
    cout << "? " << mid << endl;
    cin >> s;
    cout << "? " << mid + 1 << endl;
    cin >> t;
    if (s == "out" && t == "out") {
      r = mid;
    } else if (s == "safe" && t == "out") {
      cout << "! " << mid << endl;
      break;
    } else if (s == "out" && t == "safe") {
      cout << "! " << mid + 1 << endl;
      break;
    } else {
      l = mid;
    }
  }
  return 0;
}