Go: package main

import (
	"fmt"
	"os"
	"bufio"
	"strconv"
)

var N int
var A [][]int
var t int
var color, d, f []int

const (
	WHITE = iota
	GRAY
	BLACK
)

func dfsVisit(u int) {
	color[u] = GRAY
	t ++
	d[u] = t
	for v:=0; v<N; v++ {
		if A[u][v] == 0 {
			continue
		}
		if color[v] == WHITE {
			dfsVisit(v)
		}
	}
	color[u] = BLACK
	t++
	f[u] = t
}

func dfs() {
	for u:=0; u<N; u++ {
		if color[u] == WHITE {
			dfsVisit(u)
		}
	}
	for u:=0; u<N; u++{
		fmt.Printf("%d %d %d\n", u+1, d[u], f[u])
	}
}


func nextInt(scanner *bufio.Scanner) int {
	scanner.Scan()
	num, _ := strconv.Atoi(scanner.Text())
	return num
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	N = nextInt(scanner)
	color = make([]int, N)
	d = make([]int, N)
	f = make([]int, N)
	A = make([][]int, N)
	for i:=0; i<N; i++{
		A[i] = make([]int, N)
	}
	for i:=0; i<N; i++{
		index := nextInt(scanner) - 1
		cnt := nextInt(scanner)
		for j:=0; j<cnt; j++ {
			v := nextInt(scanner) - 1
			A[index][v] = 1
		}
	}
	dfs()
}

C++: #include<stdio.h>
#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2
int n,M[N][N];
int color[N],d[N],f[N],tt;
void dfs_visit(int u)
{
    int v;
    color[u]=GRAY;
    d[u]=++tt;
    for(v=0;v<n;v++)
    {
        if(M[u][v]==0)continue;
        if(color[v]==WHITE)
        dfs_visit(v);
    }
    color[u]=BLACK;
    f[u]=++tt;
}
void dfs()
{
    int u;
    for(u=0;u<n;u++) color[u]=WHITE;
    tt=0;
    for(u=0;u<n;u++)
    {
        if(color[u]==WHITE) dfs_visit(u);
    }
    for(u=0;u<n;u++)
    {
        printf("%d %d %d\n",u+1,d[u],f[u]);
    }
}
int main()
{
    int a,b,c;
    scanf("%d",&n);
    for(int i=0;i<n;i++)
    {
        scanf("%d %d",&a,&b);
        a--;
        for(int i=0;i<b;i++)
        {
            scanf("%d",&c);
            c--;
            M[a][c]++;
        }
    }
    dfs();
    return 0;
}

C++: #include <stdio.h>
#include <vector>
#include <algorithm>
#define rep(i, n) for(int i = 0; i < n; ++i)
using namespace std;

typedef long long ll;

ll d[100], f[100], now, cnt;
char flag[100];
vector<int> vec[100];

int dfs(int n) {
  if(flag[n]) return 0;
  flag[n] = 1;
  cnt++;
  d[n] = cnt;
  vector<int>::iterator it;
  for(it = vec[n].begin(); it != vec[n].end(); ++it) {
    if(!flag[*it]) dfs(*it);
  }
  ++cnt;
  f[n] = cnt;
  return 0;
}

int main(void) {
  ll n;
  scanf("%d", &n);
  now = 0, cnt = 0;
  rep(i, n) flag[i] = 0;
  rep(i, n) {
    int u, k;
    scanf("%d%d", &u, &k);
    u--;
    rep(j, k) {
      int v;
      scanf("%d", &v);
      v--;
      vec[u].push_back(v);
    }
    sort(vec[u].begin(), vec[u].end());
  }
  now = 0;
  while( 1 ) {
    dfs(now);
    int s = 1, i;
    for(i = 0; i < n; ++i) if(!flag[i]){
      s = 0;
      break;
    }
    if(s) break;
    else now = i;
    //rep(j, n) printf("%d ", (int)flag[j]);
    printf("%d\n", i);
    //return 0;
  }
  rep(i, n) printf("%d %lld %lld\n", i + 1, d[i], f[i]);
  return 0;
}

C++: //
//  main.cpp
//  DFS
//
//  Created by 2594345669 on 2016/12/05.
//  Copyright ?? 2016??´ as. All rights reserved.
//

#include <iostream>
using namespace std;

typedef pair<int, int> edge;

int vernum[101];
edge path[101][101];
int n;

edge found[101];

int t=1;
void dfs(int v){
    found[v].first = t;
    int i=0;
    while(1){
        if(!path[v][i].first)
            break;
        if(!found[path[v][i].second].first){
            t++;
            dfs(path[v][i].second);
            t++;
        }
        i++;
    }
    found[v].second = t+1;
}

int main() {
    int i, j;
    ios_base::sync_with_stdio(0);
    
    int e, v;
    cin >> n;
    
    for(i=1; i<=n; i++){
        cin >> vernum[i];
        cin >> e;
        for(j=0; j<e; j++){
            cin >> v;
            path[i][j] = make_pair(i, v);
        }
    }
    
    for(i=1; i<=n; i++){
        if(!found[i].first)
            dfs(i);
    }
    
    for(i=1; i<=n; i++){
        cout << vernum[i] << " " << found[i].first << " " << found[i].second << endl;
    }
    
    
    return 0;
}

C++: #include<iostream>
using namespace std;
int n,i,j,x,y,nx;
int map[100][100]={0};
int color[100]={0};//0 null  1 gray 2 black 
int start[100]={0};
int end[100]={0};
int pretime=0;
int dfs(int p){
	for(int m=0;m<n;m++){
		if(map[p][m]==1&&color[m]==0){
			start[m]=++pretime;
			color[m]=1;
			dfs(m);
		}
	}
	end[p]=++pretime;
	color[p]=2;
	return 0;
}
int main(){
	cin>>n;
	for(i=0;i<n;i++){
		cin>>x>>nx;
		for(j=0;j<nx;j++){
			cin>>y;
			map[x-1][y-1]=1;
		}
	}
	for(i=0;i<n;i++){
		if(color[i]==0){
			color[i]=1;
		    start[i]=++pretime;
	     	dfs(i);
		}

	}

	for(i=0;i<n;i++){
		cout<<i+1<<" "<<start[i]<<" "<<end[i]<<endl;
	}
	
	
	return 0;
}

C++: #include <bits/stdc++.h>
typedef long long ll;
using namespace std;
ll MOD = 1000000007;

#define vec                vector<int>
#define vecll              vector<ll>
#define vecd               vector<double>
#define vecst              vector<string>
#define vecb               vector<bool>
#define vec2(var, n, m)    vector<vector<int>> var(n, vector<int>(m, 0))
#define vecll2(var, n, m)  vector<vector<ll>> var(n, vector<ll>(m, 0))

#define rep(i,n)         for(ll i=(ll)0; i<(ll)n; i++)
#define REP(i,m,n)       for(ll i=(ll)m; i<(ll)n; i++)
#define arr(var, n)      vec var(n); rep(i,n){cin >> var[i];}
#define arrll(var, n)    vecll var(n); rep(i,n){cin >> var[i];}
#define arrst(var, n)    vecst var(n); rep(i,n){cin >> var[i];}
#define all(var)         (var).begin(), (var).end()
#define sortall(var)     sort(all(var))
#define uniqueall(v)     v.erase(unique(v.begin(), v.end()), v.end());
#define f_sum(var)       accumulate(all(var), 0)
#define f_sumll(var)     accumulate(all(var), 0LL)
#define chmin(v1, v2)    v1 = min(v1, v2)
#define chmax(v1, v2)    v1 = max(v1, v2)
#define pb(var)          push_back(var)
#define prt(var)         cout << (var) << "\n"
#define prtd(n, var)     cout << fixed << setprecision(n) << var << "\n"
#define prtfill(n, var)  cout << setw(n) << setfill('0') << var;
#define prt2(v1, v2)     cout << v1 << " " << v2 << "\n"
#define prt3(v1, v2, v3) cout << v1 << " " << v2 << " " << v3 << "\n"
#define prtall(v)        rep(i,v.size()){cout<<v[i]<<(i!=v.size()-1?" ":"\n");}
void prtok(bool ok){prt(ok ? "yes" : "no");}
//----------------------------------------------------------------
class Graph{

public:
  vector<vector<int> > graphs;
  vector<bool> check; // For DFS
  vector<ll> dist;   // For BFS
  queue<int> q; // For BFS

  vector<int> d;
  vector<int> f;
  int t;

  Graph(int n){
    graphs.resize(n);
    init(n);
  }
  ~Graph(){}

  void addedge(int u, int v){
    u--; v--;
    graphs[u].push_back(v);
    graphs[v].push_back(u);
  }

  void addedge_cin(int m){
    rep(i,m){
      int a, b;
      cin >> a >> b;
      addedge(a, b);
    }
  }

  void init(int n){
    check.resize(n, false);
    dist.resize(n, -1);
    d.resize(n, -1);
    f.resize(n, -1);
  }

  void reset(){
    rep(i,check.size()){
      check[i]=false;
      dist[i]=-1;
    }
  }

  void dfs(int v)
  {
    t++;
    check[v] = true;
    d[v] = t;

    for(int next_v : graphs[v]){
      if(check[next_v]) continue;
      dfs(next_v);
    }
    t++;
    f[v] = t;
  }

  void bfs(int v)//----------------------
  {
    dist[v] = 0;
    q.push(v);

    while(!q.empty()){
      int cur_v = q.front();
      q.pop();

      for(int next_v : graphs[cur_v]){
        if(dist[next_v] != -1){
          continue;
        }

        dist[next_v] = dist[cur_v] + 1;
        q.push(next_v);
      }
    }
  }//-----------------------

};

int main(void) {
  int n;
  cin >> n;
  Graph g(n);

  rep(i,n){
    int vertex, num;
    cin >> vertex >> num;
    vertex--;
    if(num==0) continue;
    rep(j,num){
      int tmp;
      cin >> tmp;
      tmp--;
      g.graphs[vertex].pb(tmp);
    }
    sortall(g.graphs[vertex]);
  }

  g.t = 0;
  rep(i,n){
    if(!g.check[i]){
      g.dfs(i);
    }
  }

  rep(i,n){
    prt3(i+1, g.d[i], g.f[i]);
  }
}