#include <iostream>
#include <string>
using namespace std;

int main(){
	auto numMin=10;
	auto numMax=1000000001;
	auto turn=0;
	for(;;){
		int chkNum=turn==0? 100: (numMin+numMax)/2;
		cout<<"? "<<chkNum<<endl;
		string chk;
		cin>>chk;
		if(chk=="1") numMin=chkNum;
		else if(chk=="-1") numMax=chkNum;
		else{
			cout<<"! "<<chkNum+turn<<endl;
			break;
		}
		if(0<numMin) numMin--;
		numMax--;
		turn++;
	}
	return 0;
}