#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[8]={-1,0,1,0,1,1,-1,-1};
const ll dx[8]={0,-1,0,1,1,-1,1,-1};
template <typename T> inline bool chmax(T &a, T b) {
  return ((a < b) ? (a = b, true) : (false));
}
template <typename T> inline bool chmin(T &a, T b) {
  return ((a > b) ? (a = b, true) : (false));
}
ll counter=110;
void output(ll t){
  cout << "? " << t << endl;//<<" " << counter <<endl;
  //counter--;
}
int main(){
  //cout << "? " <<80 <<endl;
  output(80);
  ll x;cin  >> x;
  if(x==0)cout <<"! " << 80 <<endl,exit(0);
  if(x==-1){
    ll cnt=1;
    while(1){
      output(0);
      cin >> x;if(x==0)cout << "! " << cnt <<endl,exit(0);
      cnt++;
    }
  }
  ll cnt=1;
  ll ok=inf-10,ng=0;
  while(ok-ng>1){
    output((ok+ng)/2);
    cin >> x;
    if(x==0)cout << "! " << cnt+(ok+ng)/2 <<endl,exit(0);
    if(x==-1)ok=(ok+ng)/2;
    else ng=(ok+ng)/2;
    cnt++;
  }
  while(1){
    output(ok-40); 
    cin >> x;
    if(x==0)cout << "! " << ok-40+cnt <<endl,exit(0);
    cnt++;
  }
}