import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int l = 1;
    int r = (int)Math.pow(10, 9) + 1;
    int ans = 0;
    while(l < r) {
      int med = (l + r) / 2;
      System.out.println("?" + " " + med);
      System.out.flush();
      int ret = sc.nextInt();
      if(ret == 1) {
        ans = med;
        l = med + 1;
      } else {
        r = med;
      }
    }
    System.out.println("!" + " " + ans);
    System.out.flush();
  }
}