func_code_string: #include <bits/stdc++.h>   using namespace std;   template <typename T>   vector<T>& operator--(vector<T>& v) {     for (auto& i : v) --i;     return v;   }   template <typename T>   vector<T>& operator++(vector<T>& v) {     for (auto& i : v) ++i;     return v;   }   template <typename T>   istream& operator>>(istream& is, vector<T>& v) {     for (auto& i : v) is >> i;     return is;   }   template <typename T>   ostream& operator<<(ostream& os, vector<T>& v) {     for (auto& i : v) os << i <<    ;     return os;   }   template <typename T, typename U>   istream& operator>>(istream& is, pair<T, U>& p) {     is >> p.first >> p.second;     return is;   }   template <typename T, typename U>   ostream& operator<<(ostream& os, pair<T, U>& p) {     os << p.first <<     << p.second;     return os;   }   template <typename T, typename U>   pair<T, U> operator-(pair<T, U> a, pair<T, U> b) {     return make_pair(a.first - b.first, a.second - b.second);   }   template <typename T, typename U>   pair<T, U> operator+(pair<T, U> a, pair<T, U> b) {     return make_pair(a.first + b.first, a.second + b.second);   }   template <typename T, typename U>   void umin(T& a, U b) {     if (a > b) a = b;   }   template <typename T, typename U>   void umax(T& a, U b) {     if (a < b) a = b;   }   const int K = 15;   array<array<bool, 1 << K>, K> dp;   int main() {     int k;     cin >> k;     vector<vector<int>> v(k);     map<int, int> where;     vector<long long> sms(k, 0);     long long need = 0;     for (int i = 0; i < k; ++i) {       int n;       cin >> n;       v[i].resize(n);       cin >> v[i];       for (auto u : v[i]) {         where[u] = i;         sms[i] += u;         need += u;       }     }     if (need % k != 0) {       cout <<  No n ;       return 0;     }     need /= k;     vector<map<int, pair<int, int>>> from(k);     for (int i = 0; i < k; ++i) {       for (int j = 0; j < v[i].size(); ++j) {         int next = need - (sms[i] - v[i][j]);         if (where.count(next)) {           from[i][v[i][j]] = make_pair(next, where[next]);         } else {           from[i][v[i][j]] = make_pair(0, -1);         }       }     }     set<int> used;     vector<pair<int, int>> sth;     for (int i = 0; i < k; ++i) {       for (int j = 0; j < v[i].size(); ++j) {         int start = v[i][j];         if (used.count(start)) continue;         int start_i = i;         int now = start;         int visited = 1 << i;         bool ok = true;         vector<int> was = {start};         while (true) {           auto [next, next_i] = from[start_i][start];           if (next_i == -1) {             ok = false;             break;           }           if (visited & (1 << next_i)) {             if (next != now) {               ok = false;             }             break;           }           visited |= (1 << next_i);           start = next;           start_i = next_i;           if (used.count(start)) {             ok = false;             break;           }           was.push_back(start);         }         if (ok) {           for (auto y : was) {             used.insert(y);           }           sth.emplace_back(visited, now);         }       }     }     dp[0].fill(false);     for (auto [mask, s] : sth) {       dp[0][mask] = true;     }     dp[0][0] = true;     for (int i = 1; i < k; ++i) {       for (int j = 0; j < (1 << k); ++j) {         int mask = j;         int submask = mask;         if (j == 0) {           dp[i][mask] = true;         } else {           dp[i][mask] = false;         }         while (submask != 0) {           if (dp[i - 1][submask] && dp[i - 1][mask ^ submask]) {             dp[i][mask] = true;             break;           }           submask = (submask - 1) & mask;         }       }     }     if (!dp[k - 1][(1 << k) - 1]) {       cout <<  No n ;       return 0;     }     cout <<  Yes n ;     vector<int> masks = {(1 << k) - 1};     for (int i = k - 1; i > 0; --i) {       vector<int> new_masks;       for (auto mask : masks) {         int submask = mask;         while (submask != 0) {           if (dp[i - 1][submask] && dp[i - 1][mask ^ submask]) {             if (submask) new_masks.push_back(submask);             if (mask ^ submask) new_masks.push_back(mask ^ submask);             break;           }           submask = (submask - 1) & mask;         }       }       swap(new_masks, masks);     }     sort(sth.begin(), sth.end());     42;     ;     vector<int> starts;     vector<pair<pair<int, int>, int>> ans;     for (auto mask : masks) {       auto it =           lower_bound(sth.begin(), sth.end(), make_pair(mask, (int)(-1e9 - 10)));       assert(it->first == mask);       int start = it->second;       int now = start;       int now_i = where[start];       int visited = 1 << now_i;       vector<pair<int, int>> path;       path.emplace_back(now_i, now);       while (true) {         auto [next, next_i] = from[now_i][now];         if (visited & (1 << next_i)) {           break;         }         now = next;         now_i = next_i;         path.emplace_back(now_i, now);         visited |= 1 << next_i;       }       for (int i = 0; i < path.size(); ++i) {         ans.emplace_back(path[i],                          path[(i - 1 + path.size()) % path.size()].first);       }     }     sort(ans.begin(), ans.end());     for (auto [p, y] : ans) {       cout << p.second <<     << y + 1 << endl;     }     return 0;   }   