#define _CRT_SECURE_NO_WARNINGS
//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
//#define int ll
//#define endl "\n"
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;
#define all(c) (c).begin(), (c).end()
#define loop(i,a,b) for(ll i=a; i<ll(b); i++)
#define rep(i,b) loop(i,0,b)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
template<class T> ostream & operator<<(ostream & os, vector<T> const &);
template<int n, class...T> typename enable_if<(n>=sizeof...(T))>::type _ot(ostream &, tuple<T...> const &){}
template<int n, class...T> typename enable_if<(n< sizeof...(T))>::type _ot(ostream & os, tuple<T...> const & t){ os << (n==0?"":" ") << get<n>(t); _ot<n+1>(os, t); }
    template<class...T> ostream & operator<<(ostream & os, tuple<T...> const & t){ _ot<0>(os, t); return os; }
template<class T, class U> ostream & operator<<(ostream & os, pair<T,U> const & p){ return os << "(" << p.first << ", " << p.second << ") "; }
template<class T> ostream & operator<<(ostream & os, vector<T> const & v){ rep(i,v.size()) os << v[i] << (i+1==(int)v.size()?"":" "); return os; }
template<class T> inline bool chmax(T & x, T const & y){ return x<y ? x=y,true : false; }
template<class T> inline bool chmin(T & x, T const & y){ return x>y ? x=y,true : false; }
#ifdef DEBUG
#define dump(...) (cerr<<#__VA_ARGS__<<" = "<<mt(__VA_ARGS__)<<" ["<<__LINE__<<"]"<<endl)
#else
#define dump(...)
#endif
ll const mod = 129402307;//1000000007;
// ll const inf = 1LL<<60;

bool firstwin(ll n, ll k){
    if(n <= k) return true;
    if((n-1)%(k+1) == 0) return false; else return true;
}

ll modpow(ll x, ll y){
    if(y==0) return 1;
    ll res = modpow(x,y/2);
    return res * res % mod * (y&1 ? x : 1) % mod;
}

ll modstr(string const & s, ll M){
    ll a = 0;
    rep(i,s.size()) a = (s[i]-'0'+ a*10) % M;
    return a;
}

ll conv(string & s){
    stringstream ss;
    ss << s;
    ll x;
    ss >> x;
    return x;
}

int g(int n){
    return (1+n)*n/2;
}

int f(int n){
    if(n&1) return (n+1)/2 + f(n-1);
    else return g(n/2)*2;
}


int ask(int Y){
    cout << "? " << Y << endl;
    int res;
    cin >> res;
    return res;
}

void repp(int Y){
    cout << "! " << Y << endl;
    return;
}

int solve(){
    if(ask(35) == -1){
        int t = 0;
        while(ask(0)) t++;
        return t;
    }
    int l = 10, r = 1000000000;
    int t = 0;
    while(l+1 < r){
        if(l==r) return l;
        int m = (l+r)/2;
        int x = ask(m-t);
        if(x==1) l = m+1;
        else if(x==-1) r = m;
        else if(x==0) return m;
        t++;
    }
}

int main(){
    repp(solve());
}