#include <bits/stdc++.h>
#define REP(i,n) for(int i = 0; i < (int)(n); ++i)
using namespace std;

int main(){
    long long hi = 1000000001;
    long long lo = 0;
    long long mid;
    int temp;
    while(hi-lo>1){
        long long mid = (hi + lo) / 2;
        cout << "? " << mid << endl;
        cin >> temp;
        temp==1?lo=mid:hi=mid;
    }
    cout << "! " << lo << endl;
    return 0;
}