#include <bits/stdc++.h>
using namespace std;
#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repl(i,0,n)
#define mp(a,b) make_pair((a),(b))
#define pb(a) push_back((a))
#define all(x) (x).begin(),(x).end()
#define uniq(x) sort(all(x)),(x).erase(unique(all(x)),end(x))
#define fi first
#define se second
#define dbg(x) cout<<#x" = "<<((x))<<endl
template<class T,class U> ostream& operator<<(ostream& o, const pair<T,U> &p){o<<"("<<p.fi<<","<<p.se<<")";return o;}
template<class T> ostream& operator<<(ostream& o, const vector<T> &v){o<<"[";for(T t:v){o<<t<<",";}o<<"]";return o;}

#define INF 2147483600

int ask(int n){
  cout << "? " << n << endl;
  int r;
  cin>>r;
  return r;
}

int main(){
  int ret = ask(100);

  if(ret==0){
    cout << "! 100" << endl;
  } else if(ret==-1){
    int cnt = 0;
    do {
      ret = ask(9);
      cnt++;
    } while(ret != 0);
    cout << "! " << 9 + cnt << endl;
  } else {
    // にぶたん
    int l=100, r=INF/2;
    int cnt = 1;
    while(r-l>1){
      int m = (l+r)/2;
      ret = ask(m-cnt);
      if(ret==0){
        cout << "! " << m <<endl;
        return 0;
      }

      if(ret == -1) r = m;
      else l = m;

      cnt++;
    }

    ret = ask(l-cnt);
    if(ret==0) cout << "! " << l << endl;
    else if(ret==1) cout << "! " << r << endl;
    else assert(false);
  }

  return 0;
}