import std.stdio;
import std.string;
import std.conv;

void main(){
	auto numMin=10;
	auto numMax=1000000001;
	auto turn=0;
	for(;;){
		int chkNum=turn==0? 100: (numMin+numMax)/2;
		writeln(text("? ",chkNum));
		stdout.flush();
		auto chk=readln().strip();
		if(chk=="1") numMin=chkNum;
		else if(chk=="-1") numMax=chkNum;
		else{
			writeln(text("! ",chkNum+turn));
			stdout.flush();
			break;
		}
		if(0<numMin) numMin--;
		numMax--;
		turn++;
	}
}