#include<iostream>
using namespace std;
int ask(int Y)
{
	cout<<"? "<<Y<<endl;
	int ret;
	cin>>ret;
	return ret;
}
main()
{
	int fst=ask(100);
	int ans;
	if(fst==0)
	{
		ans=100;
	}
	else if(fst<0)
	{
		int tm=1;
		for(;;)
		{
			if(ask(9)==0)break;
			tm++;
		}
		ans=tm+9;
	}
	else
	{
		int L=100,R=1e9+1;
		int tm=1;
		while(R-L>1)
		{
			int M=(L+R)/2;
			if(ask(M-tm)<0)R=M;
			else L=M;
			tm++;
		}
		ans=L;
	}
	cout<<"! "<<ans<<endl;
}