#include <iostream>
#include <vector>
#include <map>
#include <algorithm>
using namespace std;

#define REP(i,s,e) for (i = s; i <= e; i++)
#define rep(i,n) REP (i,0,(int)(n)-1)
#define RREP(i,s,e) for (i = s; i >= e; i--)
#define rrep(i,n) RREP (i,(int)(n)-1,0)
#define INF (int)1e8
#define MOD (int)(1e9+7)

typedef long long ll;

int main(void) {
    ll l, r, m;
    int cnt = 0;
    l = 0; r = 1e9+1; m = 100;
    while (l + 1 <= r) {
        int res;
        cout << "?" << m << endl;
        cin >> res;
        if (res == 0) {
            cout << "!" << m + cnt << endl;
            return 0;
        }
        else if (res > 0) {
            l = m;
        }
        else {
            r = m-1;
            l--;
        }
        cnt++;
        m = (l + r) / 2;
    }
    return 0;
}