import java.util.*; public class Main { public static void main(String[] args) { Scanner sc = new Scanner(System.in); int min=1; int max=1000000000; while(true){ int mid=(max+min)/2; System.out.println("? "+mid); System.out.flush(); int x = sc.nextInt(); if(x==1){ min=mid; }else{ max=mid; } if(max==min){ System.out.println("! "+max); System.out.flush(); break; } } } }