#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<int, int> PII;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define MOD 1000000007
#define INF (1LL<<25)     //33554432
#define PI 3.14159265359
#define EPS 1e-12
//#define int ll

signed main(void)
{
  int high = 1000000000, low = 1;

  while(high - low > 1) {
    int mid = (high+low)/2;
    cout << "? " << mid << endl;
    int tmp;
    cin >> tmp;
    if(tmp) {
      low = mid;
    } else {
      high = mid;
    }
  }

  cout << "! " << low << endl;

  return 0;
}