import java.util.*;
public class Question{
	public static void main(String... args){
		Scanner scan = new Scanner(System.in);
		Judge(scan);
	}
	public static void Judge(Scanner scan){
		int high = 1000000000+1;
		int low = 0;
		while(high - low > 1){
			int middle = high+low/2;
			System.out.println("? "+middle);
			int res = scan.nextInt();
			if(res==1){
				low = middle;
			}else{
				high = middle;
			}
		}
		System.out.println("! "+low);
	}
}