#include<bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
using namespace std;
typedef long long ll;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
main(){
    int cnt = 1,num;
    cout << "? 100" << endl;
    fflush(0);
    cin >> num;
    int ok,ng;
    if(num == 0){
        cout << "! 100" << endl;
        return 0;
    }else if(num == -1){
       ok = 100,ng = 0;
    }else{
        ok = INF,ng = 10;
    }
    while(num){
        int mid = (ok + ng) / 2;
        cout << "? " << mid << endl;
        fflush(0);
        cin >> num;
        if(num == 1)ng = mid;
        else if(num == -1)ok = mid;
        else cout << "! " << mid+cnt << endl;
        ok--;
        ng--;
        cnt++;
    }
    fflush(0);

}