func_code_string: #include <bits/stdc++.h>   using namespace std;   using ll = long long;   const int INF = 1000000000;   const ll LINF = 1001002003004005006ll;   int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};   template <class T>   bool chmax(T &a, const T &b) {     if (a < b) {       a = b;       return true;     }     return false;   }   template <class T>   bool chmin(T &a, const T &b) {     if (b < a) {       a = b;       return true;     }     return false;   }   template <typename T>   ostream &operator<<(ostream &os, const vector<T> &v) {     for (int i = 0; i < (int)v.size(); i++)       os << v[i] << (i + 1 == (int)v.size() ?    :    );     return os;   }   template <typename T>   istream &operator>>(istream &is, vector<T> &v) {     for (T &x : v) is >> x;     return is;   }   signed main() {     int n;     cin >> n;     vector<int> bx;     for (int i = 0; i < (n); i++) {       cout <<  ?   << 0 <<     << i << endl;       int x;       cin >> x;       bx.push_back(x);     }     vector<int> px;     for (int i = 0; i < (n); i++) {       cout <<  ?   << i <<     << 0 << endl;       int x;       cin >> x;       px.push_back(x);     }     int cnt = 0;     vector<int> print_res;     for (int i = 0; i < (n); i++) {       bool f = true;       vector<int> b;       for (auto x : bx) b.push_back(x ^ i);       auto v = b;       sort(begin(v), end(v));       for (int j = 0; j < (n); j++)         if (v[j] != j) f = false;       if (!f) continue;       vector<int> p;       for (auto x : px) p.push_back(x ^ b[0]);       for (int j = 0; j < (n); j++)         if (p[b[j]] != j) f = false;       if (!f) continue;       cnt++;       print_res = p;     }     cout <<  !  << endl;     cout << cnt << endl;     cout << print_res << endl;     return 0;   }   