#include <iostream>
using namespace std;
int ask(int Y){
	cout << "? " << Y << endl;
  int res;
	cin >> res;
	return res;
}
int main(){
	int ans = 0;
  int X = 0;
  int Y = 1000000000;
  int cnt=0;
	for(int i=0;i<100;i++){
		int Z = (X+Y)/2;
    cnt+=1;
    int a=ask(Z);
		if(a==0){
			ans = Z;
			break;
		} else if(a==1){
      X=Z;
    } else if(a==-1){
      Y=Z;
    }
    if(X>0) X-=1;
    if(Y>0) Y-=1;
	}
  ans+=cnt;
	cout << "! " << ans << endl;
	return 0;
}