#include<bits/stdc++.h>
using namespace std;
int main()
{
  cout << "? 0" << endl;
  int X0; cin >> X0;
  cout << "? 1" << endl;
  int X1; cin >> X1;
  cout << "! " << ( X0 < X1 ? -X0 : X0 ) << endl;
}