#include<stdio.h>

 #include<string.h>

 #include<algorithm>

 using namespace std;

 const int maxn = ;

 struct Node {

     int u;

     int v;

     int next;

 };

 struct Edge{

     int u;

     int v;

 };

 Edge edge[maxn];

 Node node[maxn * ];

 int head[maxn];

 int dfn[maxn];

 int low[maxn];

 int fath[maxn];

 bool vis[maxn];

 bool maps[maxn][maxn];

 int n, tol, cnt;

 void init() {

     cnt = tol= ;

     memset(dfn, , sizeof(dfn));

     memset(low, , sizeof(low));

     memset(maps, , sizeof(maps));

     memset(fath, , sizeof(fath));

     memset(head, -, sizeof(head));

     memset(vis, false, sizeof(vis));

 }

 void addnode(int u, int v) {

     node[tol].u = u;

     node[tol].v = v;

     node[tol].next = head[u];

     head[u] = tol++;

 }

 void dfs(int u, int fa){

     fath[u] = fa;

     low[u] = dfn[u] = ++cnt;

     vis[u] = true;

     for(int i=head[u]; i!=-; i=node[i].next) {

         int v = node[i].v;

         if(!dfn[v]) {

             dfs(v, u);

             low[u] = min(low[u], low[v]);

         } else if(v != fa) {

             low[u] = min(low[u], dfn[v]);

         }

     }

 }

 void tarjan() {

     for(int u=; u<n; u++) {

         if(!dfn[u]) {

             dfs(u, u);

         }

     }

 }

 bool cmp(Edge a, Edge b) {

     if(a.u == b.u)

         return a.v < b.v;

     else

         return a.u < b.u;

 }

 void solve() {

     tol = ;

     for(int u=; u<n; u++) {

         int v = fath[u];

         if(low[u] > dfn[v] && v != u) {

             edge[tol].u = u;

             edge[tol].v = v;

             if(edge[tol].u > edge[tol].v)

                 swap(edge[tol].u, edge[tol].v);

             tol++;

         }

     }

     sort(edge, edge+tol, cmp);

     printf("%d critical links\n", tol);

     for(int i=; i<tol; i++) {

         printf("%d - %d\n", edge[i].u, edge[i].v);

     }

     printf("\n");

 }

 int main() {

     while(scanf("%d", &n) != EOF) {

         init();

         if(n == ) {

             printf("0 critical links\n\n");

             continue;

         }

         for(int i=; i<=n; i++) {

             int u;

             int num;

             scanf("%d (%d)", &u, &num);

             for(int j=; j<=num; j++) {

                 int v;

                 scanf("%d", &v);

                 maps[u][v] = maps[v][u] = ;

             }

         }

         for(int i=; i<n; i++) {

             for(int j=i+; j<n; j++) {

                 if(maps[i][j]) {

                     addnode(i, j);

                     addnode(j, i);

                 }

             }

         }

         tarjan();

         solve();

     }

     return ;

 }