#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
using namespace std;

int main()
{
    int a = 1;
    int b = 1000000000;
    while(a < b){
        int y = (a + b + 1) / 2;
        cout << "? " << y << endl;

        int res;
        cin >> res;
        if(res == 0)
            b = y - 1;
        else
            a = y;
    }
    cout << "! " << a << endl;

    return 0;
}