using System;

class Program{
	static void Main(){
		var numMin=10;
		var numMax=1000000001;
		var turn=0;
		for(;;){
			int chkNum=turn==0? 100: (numMin+numMax)/2;
			Console.WriteLine($"? {chkNum}");
			var chk=Console.ReadLine();
			if(chk=="1") numMin=chkNum;
			else if(chk=="-1") numMax=chkNum;
			else{
				Console.WriteLine($"! {chkNum+turn}");
				break;
			}
			if(0<numMin) numMin--;
			numMax--;
			turn++;
		}
	}
}