#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n);i++)
#define sz(x) int(x.size())
typedef long long ll;
typedef long double ld;
typedef pair<int,int> P;

int main() {
  vector<int> ok(1001, 1);
  string ret = 0;
  int x = 100000;
  for (int i = 2; i <= 1000; i++) {
    if (!ok[i]) continue;
    for (int j = i; j <= 1000; j += i) ok[j] = 0;
    cout << "? ";
    cout << i << endl;
    cout.flush();
    cin >> ret;
    if (ret == "out") {
      x = i;
      break;
    }
  }

  vector<int> v;
  v.emplace_back(0);
  for (int i = 1; i <= 1000; i++) if (i % x != 0) v.emplace_back(i);

  int l = -1, r = v.size();

  while ( r - l > 1) {
    int m = (r + l) / 2;
    cout << "? ";
    cout << v[m];
    cout.flush();
    cin >> ret;
    if (ret == "out") r = m;
    else l = m;
  }
  cout << "! ";
  cout << v[l] << endl;
  return 0;
}