#include <algorithm>
#include <array>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <ostream>
#include<complex>
#include <cmath>
#include <iostream>
#include <stack>
#include <fstream>
#include <queue>
#include <list>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <bitset>
#include <iomanip>
#include <string>
#include <vector>
#include <string>
using namespace std;
#define OB (bitset<32>)
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define ALLOF(c) begin(), (c),end()

typedef long long ll;

#define PI acos(-1)
#define EPS 0.000000001
#define MOD 1000000007

//k ijyou?
bool func(int k)
{
    int ans;
    cout << "? " << k << endl;
    cin >> ans;
    return ans == 1 ? true: false;
}
int main()
{  
    int mid;
    int low = 0;
    int hi = MOD;
    while(hi > low + 1)
    {
        mid = (hi + low)/2;
        if(func(mid))
        {
            low = mid;
        }
        else
        {
            hi = mid;
        }
    }
    cout << "! " << low << endl; 
    return 0;
}