func_code_string: #include <bits/stdc++.h>   using namespace std;   const int Maxn = 300005;   int res, cnt, head[Maxn], choose[Maxn], target[Maxn], las[Maxn], ct, n[Maxn], k,       val[Maxn], a[20][Maxn], b[Maxn], bel[Maxn], state_cnt;   bool vis1[Maxn], vis2[Maxn], ans[Maxn], done[20], flag;   map<long long, int> Ma;   long long sum[Maxn], tot;   int tmp_state, Solution[Maxn][20], Solution_cnt;   struct edg {     int nxt, to;   } edge[2 * Maxn];   void add(int x, int y) {     if (bel[x] == bel[y]) return;     if (done[bel[x]] || done[bel[y]]) return;     edge[++cnt] = (edg){head[x], y};     head[x] = cnt;   }   void dfs(int u) {     vis1[u] = true;     vis2[u] = true;     for (int i = head[u]; i; i = edge[i].nxt) {       int to = edge[i].to;       if (vis2[to]) {         res = to;         tmp_state = 0;         state_cnt++;         tmp_state |= (1 << (bel[to] - 1));         tmp_state |= (1 << (bel[u] - 1));         vis2[u] = false;         Solution[state_cnt][1] = to, Solution[state_cnt][2] = u;         Solution_cnt = 2;         return;       }       dfs(to);       if (flag) return;       if (tmp_state & (1 << (bel[u] - 1))) {         if (res == u)           val[state_cnt] = tmp_state,           reverse(Solution[state_cnt] + 1,                   Solution[state_cnt] + Solution_cnt + 1),           Solution[state_cnt][Solution_cnt + 1] = Solution[state_cnt][1],           tmp_state = 0;         else           state_cnt--, tmp_state = 0;         flag = true;         return;       } else if (tmp_state) {         tmp_state |= (1 << (bel[u] - 1));         Solution[state_cnt][++Solution_cnt] = u;         vis2[u] = false;         return;       }     }     vis2[u] = false;   }   void get_ans(int id) {     choose[bel[Solution[id][1]]] = b[Solution[id][1]];     for (int i = 2; Solution[id][i]; i++) {       choose[bel[Solution[id][i]]] = b[Solution[id][i]];       target[bel[Solution[id][i - 1]]] = bel[Solution[id][i]];     }   }   int main() {     scanf( %d , &k);     for (int i = 1; i <= k; i++) {       scanf( %d , &n[i]);       for (int j = 1; j <= n[i]; j++)         scanf( %d , &a[i][j]), b[++ct] = a[i][j], sum[i] += a[i][j],                                tot += a[i][j];     }     if (tot % k) {       printf( NO );       return 0;     }     tot /= k;     for (int i = 1; i <= k; i++)       if (tot == sum[i]) done[i] = true;     sort(b + 1, b + 1 + ct);     for (int i = 1; i <= k; i++)       for (int j = 1; j <= n[i]; j++)         Ma[a[i][j]] = lower_bound(b + 1, b + 1 + ct, a[i][j]) - b,         bel[Ma[a[i][j]]] = i;     for (int i = 1; i <= k; i++)       for (int j = 1; j <= n[i]; j++)         if (Ma[tot - sum[i] + a[i][j]])           add(Ma[tot - sum[i] + a[i][j]], Ma[a[i][j]]);     for (int i = 1; i <= ct; i++)       if (!vis1[i]) flag = false, dfs(i);     for (int i = 1; i <= k; i++)       if (sum[i] == tot) val[++state_cnt] = 1 << (i - 1);     int maxi = (1 << k) - 1;     ans[0] = true;     for (int i = 0; i <= maxi; i++)       if (ans[i])         for (int j = 1; j <= state_cnt; j++)           if (!(val[j] & i)) ans[val[j] | i] = true, las[val[j] | i] = j;     if (ans[maxi]) {       printf( YES n );       int state_now = maxi;       while (state_now) {         get_ans(las[state_now]);         state_now ^= val[las[state_now]];       }       for (int i = 1; i <= k; i++)         if (target[i])           printf( %d %d n , choose[i], target[i]);         else           printf( %d %d n , a[i][1], i);       return 0;     }     printf( NO );     return 0;   }   