#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>

#define FORR(i,b,e) for(int i=(b);i<(int)(e);++i)
#define FOR(i,e) FORR(i,0,e)
#define ALL(c) begin(c), end(c)
#define dump(var) cerr << #var ": " << var << "\n"
#define dumpc(con) for(auto& e: con) cerr << e << " "; cerr<<"\n"

using namespace std;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int l = 1, r = 1e9+1, m;
    while (l + 1 < r) {
        m = (l + r) / 2;
        cout << "? " << m << endl;
        int a;
        cin >> a;
        if (a) l = m;
        else r = m;
    }
    
    cout << "! " << l << endl;

    return 0;
}