#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ALL(v) v.begin(), v.end()
typedef long long ll;

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

int main() {
  int cnt=1;
  int l=0,r=1001;
  string s;
  
  cout<<"?"<<1<<endl;
  cin>>s;
  if(s=="out"){
    cout<<"!"<<0<<endl;
    return 0;
  }
  
  while(r-l>1){
    int m=(l+r)/2;
    cout<<"?"<<m<<endl;
    cin>>s;
    cnt++;
    if(s=="safe") l=m;
    else r=m;
  }
  int n=r;
  
  int i=1;
  while(cnt<=25){
    cout<<"?"<<n-i<<endl;
    cin>>s;
    cnt++;
    if(s=="safe"){
      cout<<"!"<<n-i<<endl;
      return 0;
    }
  }
  cout<<"!"<<n-i-1<<endl;

  return 0;
}