#include <bits/stdc++.h>
using namespace std;
int main(){
    int a = 1, b = 1000000000, m = (a + b) / 2;
    while((b - a) / 2 > 0){
        cout << "? "<< m << endl;
        int r;
        cin >> r;
        if(r == 1){
            a = m;
        }else{
            b = m;
        }
        m = (a + b) / 2;
    }
    cout << "! " << m << endl;
}