#include<map>
#include<iostream>
#include<deque>
#include<algorithm>
#include<string>
#include<cctype>
#include<iomanip>
#include<vector>
#include<queue>
#include<tuple>
#include<stdio.h>
 
using namespace std;
#define REP(i,b,e) for(ll i=(ll)b;i<(ll)e;i++)
#define rep0(i,n) REP(i,0ll,n)
#define rep1(i,n) REP(i,1ll,n+1)
 
#define shosu setprecision(10)
 
typedef long long ll;
typedef pair<ll,ll> P;
typedef pair<P,ll> Q;
ll longinf=1ll<<60;
int inf=1<<29;
int dh[]={1,-1,0,0};
int dw[]={0,0,1,-1};

int main(){
      int ok=1e9;
      int ng=0;
      while(ok-ng>1){
            int mid=(ok+ng)/2;
            cout<<"? "<<mid;
            fflush(stdout);
            int x;
            cin>>x;
            if(x) ng=mid;
            else ok=mid;
      }
      cout<<"! "<<ok;
      fflush(stdout);

      return 0;
}