#include <iostream>
using namespace std;
int main(){
  int n,q,r,a,ma,mi,c;
  n=100;
  ma=1e9;
  mi=1;
  c=(ma+mi)/2;
  q=c;
  while(n>0){
    cout<<"? "<<q<<endl;
    n--;
    cin>>r;
    if(r==1){
      mi=c;
      c=(ma+mi)/2;
      if(q+1==c){
        cout<<"! "<<c<<endl;
        break;
      } else {
        q=c;
      }
    } else{
      ma=c;
      c=(ma+mi)/2;
      if(q-1==c){
        cout<<"! "<<c<<endl;
        break;
      } else {
        q=c;
      }
    }
  }
  return 0;
}