package no246;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int left = 1;
		int right = (int) 1E9 + 1;
		while(left + 1 < right) {
			int c = (left + right) / 2;
			System.out.println("? " + c);
			if (sc.nextInt() == 1) {
				left = c;
			}else{
				right = c;
			}
		}
		System.out.println("! " + left);
	}

}