/* -*- coding: utf-8 -*-
 *
 * 246.cc: No.246 質問と回答 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 1000000000;

/* typedef */

/* global variables */

/* subroutines */

/* main */

int main() {
  int l = 1, r = MAX_N + 1;

  while (l + 1 < r) {
    int n = (l + r) / 2;
    printf("? %d\n", n); flush(cout);

    int res;
    cin >> res;

    if (res == 1) l = n;
    else r = n;
  }

  printf("! %d\n", l); flush(cout);
  return 0;
}