#include <iostream>
using namespace std;

int solve(int l,int r)
{
	if(r-l==1)return l;
	cout<<"? "<<(l+r)/2<<endl;
	int a;cin>>a;
	if(a)return solve((l+r)/2,r);
	else return solve(l,(l+r)/2);
}

int main() {
	cout<<"! "<<solve(1,1000000001)<<endl;
	return 0;
}