import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;

public class Main {
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		int lower = 1, upper = 1000000000; // [lower, upper)
		while(lower + 1 < upper){
			final int mid = (lower + upper) / 2;
			
			System.out.println("? " + mid);
			
			final int ops = sc.nextInt();
			
			if(ops == 1){
				lower = mid;
			}else{
				upper = mid;
			}
		}
		
		System.out.println("! " + lower);
	}
	
}