Go: package main

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

type vertexId int

type vertex struct {
	id vertexId
	firstVisitAt int
	finishVisitAt int
	adjs []vertexId
}

func createVertex(id int, adjsInt []int) vertex {
	adjs := make([]vertexId, len(adjsInt))
	for i := 0; i < len(adjs); i++ {
		adjs[i] = vertexId(adjsInt[i])
	}
	return vertex{
		id: vertexId(id),
		firstVisitAt: 0,
		finishVisitAt: 0,
		adjs: adjs,
	}
}

func (v *vertex) doesAllAdjsVisited(vertices []vertex) bool {
	for _, vId := range v.adjs {
		adj := vertices[vId-1]
		if !adj.isVisited() {
			return false
		}
	}
	return true
}

func (v *vertex) isFirstVisit() bool {
	return v.firstVisitAt == 0
}

func (v *vertex) isVisited() bool {
	return v.firstVisitAt > 0
}

func (v *vertex) nextVertex(vertices []vertex) (vertexId, error) {
	for _, vId := range v.adjs {
		adj := vertices[vId-1]
		if !adj.isVisited() {
			return vId, nil
		}
	}
	return vertexId(-1), fmt.Errorf("illegal")
}

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	timestamp = timestamp + 1
	currentVertex := &vertices[currentId-1]
	if currentVertex.isFirstVisit() {
		currentVertex.firstVisitAt = timestamp
	}
	for !currentVertex.doesAllAdjsVisited(vertices) {
		nextVertexId, _ := currentVertex.nextVertex(vertices)
		timestamp = dfs(nextVertexId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	vertices := make([]vertex, n)
	for i := 0; i < n; i++ {
		id, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjN, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjs := make([]int, adjN)
		for j := 0; j < adjN; j++ {
			adjId, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			adjs[j] = adjId
		}
		vertices[i] = createVertex(id, adjs)
	}

	dfs(vertexId(1), 0, vertices)

	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", vertices[i].id, vertices[i].firstVisitAt, vertices[i].finishVisitAt)
	}
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

func nextInt(sc *bufio.Scanner) (int, error) {
	return strconv.Atoi(nextText(sc))
}

C++: #include<bits/stdc++.h>
using namespace std;
#define int long long
vector<vector<int> > G;
int d[111],f[111],u[111];
void dfs(int v,int& p){
  if(u[v]) return;
  u[v]=1;
  sort(G[v].begin(),G[v].end());
  d[v]=++p;
  for(int u:G[v]) dfs(u,p);
  f[v]=++p;
}
signed main(){
  int n;
  cin>>n;
  G.resize(n,vector<int>());
  for(int i=0;i<n;i++){
    int u,k;
    cin>>u>>k;
    u--;
    for(int j=0;j<k;j++){
      int c;
      cin>>c;
      c--;
      G[u].push_back(c);
    }
  }
  int p=0;
  dfs(0,p);
  for(int i=0;i<n;i++) cout<<i+1<<" "<<d[i]<<" "<<f[i]<<endl;;
  return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;

#define ul unsigned long long
#define ll long long

ll g[101][101],a[101][2],ct;

void dfs(ll ci) {
  //cout<<ci<<endl;
  if (a[ci][0]) return;
  ll ni;
  ct++;
  a[ci][0]=ct;

  for (ll i = 1; i <= g[ci][0]; i++)
  {
    ni=g[ci][i];
    if (ni>0) {
      g[ci][i] = 0;
        dfs(ni);
    }
  }

  ct++;
  a[ci][1] = ct;
}

int main()
{
  ll n,ci;
  cin>>n;
  fill_n(a[0],101*2,0);
  a[0][0]=1;
  ct=0;

  for (ll i = 0; i < n; i++)
  {
    cin>>ci;
    cin>>g[ci][0];
    for (ll j = 1; j <= g[ci][0]; j++)
    {
      cin>>g[ci][j];
    }
  }

  for (ll i = 1; i <= n; i++)
  {
    dfs(i);
  }
  

  for (ll i = 1; i <= n; i++)
  {
    cout<< (i) <<" "<<a[i][0]<<" "<<a[i][1]<<endl;
  }
  

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define _GLIBCXX_DEBUG

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

void dfs(int p, vector<vector<int>> dst) {
  d[p] = t;
  for (int x : dst[p]) {
    if (!d[x]) {
      ++t;
      dfs(x, dst);
    }
  }
  f[p] = ++t;
}

int main() {
  int n;
  cin >> n;
  // bug
  vector<vector<int>> dst;
  dst = vector<vector<int>>(n + 1);
  d = vector<int>(n + 1, 0);
  f = vector<int>(n + 1, 0);
  for (int i = 1; i <= n; i++) {
    int u, k;
    cin >> u >> k;
    for (int j = 0; j < k; j++) {
      int v;
      cin >> v;
      dst[u].push_back(v);
    }
  }
  t = 0;
  // bug:未発見の頂点が残る場合を考えていなかった。
  // dfs(1, 1);
  for (int i = 1; i <= n; i++) {
    if (!d[i]) {
      ++t;
      dfs(i, dst);
    }
  }
  for (int i = 1; i <= n; i++) {
    cout << i << ' ' << d[i] << ' ' << f[i] << endl;
  }
}

C++: #include <iostream>
#include <vector>
using namespace std;

vector<int> graph[100];
int start[100],endt[100];
int cnt;

void dfs(int num){
	start[num] = ++cnt;
	for(int i = 0;i < graph[num].size();i++){
		if(graph[num][i] != num && !start[graph[num][i]] && !endt[graph[num][i]]) dfs(graph[num][i]);
	}
	endt[num] = ++cnt;
}

int main(){
	int n;
	cin >> n;
	for(int i = 0;i < n;i++){
		int now,m;
		cin >> now >> m;
		for(int j = 0;j < m;j++){
			int t;
			cin >> t;
			graph[now - 1].push_back(t - 1);
		}
	}
	dfs(0);
	for(int i = 0;i < n;i++){
		if(!endt[i]) dfs(i);
	}
	for(int i = 0;i < n;i++){
		cout << i + 1 << " " << start[i] << " " << endt[i] << endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

vector<int> d(100), f(100);
vector<vector<int>> G(100);
int cnt = 1;

void dfs(int i) {
    d[i] = cnt++;
    for (auto v : G[i]) {
        if (d[v] == 0) dfs(v);
    }
    f[i] = cnt++;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        int u, k;
        cin >> u >> k;
        for (int j = 0; j < k; j++) {
            int v;
            cin >> v;
            G[u - 1].push_back(v - 1);
        }
    }
    for (int i = 0; i < n; i++) {
        if (d[i] == 0) dfs(i);
    }
    for (int i = 0; i < n; i++) {
        cout << i + 1 << " " << d[i] << " " << f[i] << endl;
    }

    return 0;
}

C++: #include <iostream>
#include <stack>
using namespace std;
static const int N =100;
static const int white=0;
static const int gray=1;
static const int black=2;

int n,M[N][N];
int color[N],d[N],f[N],tt;
int nt[N];

int next(int u){
    for (int v=nt[u];v<n;v++){
        nt[u] = v+1;
        if(M[u][v])return v;    }
        return -1;
}

void dfs_visit(int r){
    for(int i=0;i<n;i++)nt[i]=0;
    
    stack<int>s;
    
    s.push(r);
    color[r]=gray;
    d[r]=++tt;
    
    while(!s.empty()){
        int u=s.top();
        int v=next(u);
        if(v!=-1){
            if(color[v]==white){
                color[v]=gray;
                d[v]=++tt;
                s.push(v);
            }
        }else{
            s.pop();
            color[u]=black;
            f[u]=++tt;
        }
    }
}
void dfs(){
    for(int i=0;i<n;i++){
        color[i]=white;
        nt[i]=0;
    }
    tt=0;
    for(int u=0;u<n;u++){
        if(color[u]==white)dfs_visit(u);
    }
    for(int i=0;i<n;i++){
        cout<<i+1<<" "<<d[i]<<" "<<f[i]<<endl;
        
    }
    }
    int main(){
        int u,k,v;
        cin>>n;
        for(int i=0;i<n;i++){
            for(int j=0;j<n;j++)M[i][j]=0;
        }
        for(int i=0;i<n;i++){
            cin>>u>>k;
            u--;
            for(int j=0;j<k;j++){
                cin>>v;
                v--;
                M[u][v]=1;
            }
        }
        dfs();
        return 0;
}