import java.util.*;

class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int s = 0;
		int e = 64;
		int count = 0;
		boolean al = false;
		while(s <= e) {
			System.out.println("? " + (s + e)/2);
			count++;
			int in = sc.nextInt();
			if(in == -1){
				e = (s + e)/2-1;
				s--;
			}
			if(in == 1) {
				s = (s + e)/2;
				e--;
			}
			if(in == 0) {
				al = true;
				System.out.println("! " + ((s + e)/2 + count-1));
				break;
			}
		}
		
		
		if(!al) {
			s = 0;
			e = 1000000001;
			while(true) {
				System.out.println("? " + (s + e)/2);
				count++;
				int in = sc.nextInt();
				if(in == -1){
					e = (s + e)/2-1;
					s--;
				}
				if(in == 1) {
					s = (s + e)/2;
					e--;
				}
				if(in == 0) {
					al = true;
					System.out.println("! " + ((s + e)/2 + count-1));
					break;
				}
			}
		}
	}
}