import java.util.Scanner;

class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int a = 1000000000;
		int b = 0;
		while(a - b > 1){
			System.out.println("? " + (a + b)/2);
			int in = sc.nextInt();
			if(in == 1){;
				b = (a + b)/2;
			}
			if(in == 0){
				a = (a + b)/2;
			}
		}
		System.out.println("! " + b);
		}
	}