#include<bits/stdc++.h>
using namespace std;

using ll = int_fast64_t;
#define rep(i,n) for(int i=0;i<(n);++i)

signed main(){

  auto question = [](ll x){
    cout<<"? "<<x<<endl;
    string s;
    cin>>s;
    return s;
  };
  if(question(1)=="out"){
    cout<<"! "<<0<<endl;
    return 0;
  }
  
  ll l=0,r=1e3+1;
  map<ll,string> mp;
  while(r-l>1){
    ll m = (l+r)/2;
    
    string s = (mp.count(m)?mp[m]:question(m));
    if(s=="safe"){
      mp[m] = s;
      l=m;continue;
    }
    string t = (mp.count(m+1)?mp[m+1]:question(m+1));
    if(s=="out" and t=="out"){
      r = m;
    }else{
      if(s=="safe")l=m;
      else l=m+1;
    }
    mp[m] = s;
    mp[m+1] = t;
  }
  cout<<"! "<<l<<endl;

}