#include <cstdio>

#include <cstring>

#include <string>

#include <cmath>

#include <iostream>

#include <algorithm>

#include <queue>

#include <cstdlib>

#include <stack>

#include <vector>

#include <set>

#include <map>

#define LL long long

#define mod 100000000

#define inf 0x3f3f3f3f

#define eps 1e-6

#define N 10010

#define FILL(a,b) (memset(a,b,sizeof(a)))

#define lson l,m,rt<<1

#define rson m+1,r,rt<<1|1

#define PII pair<int,int>

using namespace std;

struct edge

{

    int v,next;

    edge(){}

    edge(int v,int next):v(v),next(next){}

}e[N<<];

struct bridge

{

    int u,v;

    bridge(){}

    bridge(int u,int v):u(u),v(v){}

    bool operator<(const bridge &a)const{

        if(u==a.u)return v<a.v;

        return u<a.u;

    }

}b[N<<];

int n,step,top,tot,num;

int head[N],dfn[N],low[N],Stack[N];

bool instack[N],vis[N<<];

map<int,int>mp;

void init()

{

    tot=;step=;top=;num=;

    FILL(head,-);FILL(dfn,);

    FILL(low,);FILL(instack,false);

    FILL(vis,);mp.clear();

}

bool isHash(int u,int v)

{

    if(mp[u*N+v])return ;

    if(mp[v*N+u])return ;

    mp[u*N+v]=mp[v*N+u]=;

    return ;

}

void addedge(int u,int v)

{

    e[tot]=edge(v,head[u]);

    head[u]=tot++;

}

void tarjan(int u)

{

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

    Stack[top++]=u;

    instack[u]=true;

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

    {

        int v=e[i].v;

        if(vis[i])continue;

        vis[i]=vis[i^]=;

        if(!dfn[v])

        {

            tarjan(v);

            if(low[u]>low[v])low[u]=low[v];

            //桥：一条无向边(u,v)是桥，当且仅当(u,v)为树枝边，且满足DFS[u]<Low[v]

            if(low[v]>dfn[u])

            {

                b[num++]=bridge(min(u,v),max(u,v));

            }

        }

        else if(low[u]>dfn[v])

        {

            low[u]=dfn[v];

        }

    }

    instack[u]=false;

    top--;

}

void solve()

{

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

        if(!dfn[i])tarjan(i);

    sort(b,b+num);

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

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

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

    puts("");

}

int main()

{

    int u,v;

    while(scanf("%d",&n)>)

    {

        init();

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

        {

            int t,u,v;

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

            while(t--)

            {

                scanf("%d",&v);

                if(!isHash(u,v))

                {

                    addedge(u,v);

                    addedge(v,u);

                }

            }

        }

        solve();

    }

}