#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(){
  ll l=0,r=1e9+1;
  while(r-l>1){
    ll m=(r+l)/2;
    cout<<"? "<<m<<endl;
    ll x;
    cin>>x;
    if(x==1) l=m;
    else r=m;
  }
  cout<<"! "<<l<<endl;
 
  return 0;
}