#include <stdio.h>

#include <string.h>

#include <algorithm>

#include <math.h>

#include <vector>

#include <stack>

using namespace std;

typedef long long LL;

const int N = 1e4+;

int head[N],tot,n,cnt;

struct Edge{

   int u,v,next;

   bool operator<(const Edge& rhs)const{

     if(u!=rhs.u)return u<rhs.u;

     return v<rhs.v;

   }

}edge[N*],o[N*];

void add(int u,int v){

   edge[tot].v=v;

   edge[tot].next=head[u];

   head[u]=tot++;

}

int dfn[N],low[N],clk;

void targin(int u,int f){

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

   for(int i=head[u];~i;i=edge[i].next){

       int v=edge[i].v;

       if(v==f)continue;

       if(!dfn[v]){

         targin(v,u);

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

         if(dfn[u]<low[v]){

            ++cnt;

            o[cnt].u=min(u,v);

            o[cnt].v=max(u,v);

         }

       }

       else if(dfn[v]<low[u])low[u]=dfn[v];

   }

}

int main(){

    while(~scanf("%d",&n)){

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

      cnt=clk=tot=;

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

         int u,k;

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

         while(k--){int v;scanf("%d",&v);add(u,v);}

      }

      memset(dfn,,sizeof(dfn));

      memset(low,,sizeof(low));

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

       if(!dfn[i])targin(i,-);

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

      if(cnt)sort(o+,o++cnt);

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

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

      }

      printf("\n");

    }

    return ;

}