#include <iostream>
#include <sstream>
#include <vector>
#include <cmath>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <bitset>
#include <iomanip>
#include <algorithm>
#include <queue>
#include <numeric>
#include <functional>
using namespace std;


#define REP(i, n) for(int i = 0; i < (int)(n); i++)
#define FOR(i,n,m) for (int i=n; i<(int)(m); i++)
#define INF 1000000007

typedef long long ll;
typedef long double ld;
ll dy[4]={-1,1,0,0};
ll dx[4]={0,0,1,-1};

int main(){
    
    int ub = 1000;
    int lb = 0;
    bool ans=false;
    
    while(ub - lb > 1){
        int mid = (ub+lb)/2;
        cout << "? " << mid << endl;
        cin >> ans;
        if(ans) lb=mid;
        else ub=mid;
    }
    cout << "! " << lb << endl;
    
    return 0;
}