#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
const ll INF = LLONG_MAX / 4;
#define rep(i, a, b) for(int i = a; i < (b); i++)
#define rrep(i, a, b) for(int i = (b)-1; i >= (a); i--)
#define all(a) begin(a), end(a)
bool chmin(auto& a, auto b) {return a > b ? a = b, 1 : 0; }
bool chmax(auto& a, auto b) {return a < b ? a = b, 1 : 0; }

void solve();

int main() {
    cin.tie(0) -> sync_with_stdio(false);
    
    int t = 1;
    // cin >> t;
    while(t--) {
        solve();
    }
}


void solve() {
    int d;
    cin >> d;
    cout << "? 0" << endl;
    cout << "? 1" << endl;
    ll x,y;
    cin >> x >> y;
    cout << "! " << y - x << endl;
}