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

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	currentVertex := &vertices[currentId-1]
	if currentVertex.isVisited() {
		return timestamp
	}
	timestamp = timestamp + 1
	currentVertex.firstVisitAt = timestamp
	for _, adjId := range currentVertex.adjs {
		timestamp = dfs(adjId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

func solveDfs(vertices []vertex) {
	timestamp := 0
	for {
		vid := vertexId(-1)
		for i := 0; i < len(vertices); i++ {
			if !vertices[i].isVisited() {
				vid = vertexId(i+1)
				break
			}
		}
		if vid > 0 {
			timestamp = dfs(vid, timestamp, vertices)
		} else {
			break
		}
	}
}

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)
	}

	solveDfs(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<iostream>
#include<cmath>
#include<algorithm>
#include<vector>

using namespace std;

vector<int> F;
vector<int> L;
vector<bool> seen;

void dfs(vector<vector<int>> &G,int v,int &t){
    F[v]=t++;

    seen[v]=true;

    for(int i=0;i<G[v].size();i++){
        if(seen[G[v][i]])continue;
        dfs(G,G[v][i],t);
    }

    L[v] = t++; 
}

int main(){

    int n;
    cin >> n;

    vector<vector<int>> G(n);

    for(int i=0;i<n;i++){
        int a,k;
        cin >> a >> k;
        for(int j=0;j<k;j++){
            int b;
            cin >>b;
            G[i].push_back(b-1);
        }
    }

    seen.assign(n,false);
    F.resize(n);
    L.resize(n);
    int t=1;
    
    

    for(int i=0;i<n;i++){
        if(!seen[i])dfs(G,i,t);
        cout << i+1 << " " << F[i] << " " << L[i] << endl;
    }

    return 0;




}

C++: #include <iostream>
#include <string>
#include <vector>
#include <utility>
#include <queue>
#include <deque>
#include <stack>
#include <algorithm>
#include <bitset>
#include <cstdio>
#include <cmath>

using namespace std;

int cnt = 1; // time stamp
vector<int> seen, visited;

void dfs(vector<vector<int> > graph, int v) {
    if (seen[v] != 0) return;
    seen[v] = cnt;
    cnt++;
    for (int i = 0; i < graph[v].size(); i++) {
        dfs(graph, graph[v][i]);
    }
    visited[v] = cnt;
    cnt++;
}

int main() {
    int n;
    cin >> n;
    vector<vector<int> > graph(n+1);
    for (int i = 1; i <= n; i++) {
        int u, k;
        cin >> u >> k;
        for (int j = 0; j < k; j++) {
            int v;
            cin >> v;
            graph[u].push_back(v);
        }
    }
    seen.assign(n+1, 0);
    visited.assign(n+1, 0);
    for (int i = 1; i <= n; i++) dfs(graph, i);
    for (int i = 1; i <= n; i++) {
        cout << i << " " << seen[i] << " " << visited[i] << endl;
    }
}

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;
}

C++: #include<stdio.h>

void dfs_visit(int);
void dfs();

#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

int n,M[N][N];
int color[N],D[N],F[N],t;

int main()
{
  int i,j,u,x,y;

  scanf("%d",&n);

  for(i=0;i<n;i++)
    {
      for(j=0;j<n;j++)
        M[i][j]=0;
    }

  for(i=0;i<n;i++)
    {
      scanf("%d%d",&u,&y);
      u--;
      for(j=0;j<y;j++)
        {
          scanf("%d",&x);
          x--;
          M[u][x]=1;
        }
    }

  dfs();

  return 0;
}

void dfs_visit(int u)
{
  int v;
  color[u]=GRAY;
  D[u]=++t;

  for(v=0;v<n;v++)
    {
      if(M[u][v]==0) continue;
      if(color[v]==WHITE)
        {
          dfs_visit(v);
        }
    }
  color[u]=BLACK;
  F[u]=++t;
}

void dfs()
{
  int u;

  for(u=0;u<n;u++)
    color[u]=WHITE;

  t=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]);
}

C++: #include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define nyan "(=^･ω･^=)"
using namespace std;

const int mod = 1e9 + 7;
const long long INF = 1LL<<60;
//using ll = long long;
//using P = pair<int,int>;

int n;
int M[110][110];
int visited[110];
vector<int> d(110, 0);
vector<int> f(110, 0);
int t;

void dfs(int v){
    
    t++;
    d[v] += t;
    visited[v] = 1;
    
    for (int i = 0; i < n; i++){
        if (M[v][i] == 0) continue;
        
        if(visited[i] == 0) dfs(i);
    }
    
    visited[v] = 2;
    t++;
    f[v] += t;
}

int main(){
    cin >> n;
    t = 0;
    
    for (int i = 0; i < n; i++){
        for (int j = 0; j < n; j++) M[i][j] = 0;
        visited[i] = 0;
    }
    
    for (int i = 0; i < n; i++){
        int u;
        cin >> u;
        u--;
        
        int k;
        cin >> k;
        
        for (int j = 0; j < k; j++){
            int v;
            cin >> v;
            v--;
            
            M[u][v]++;
        }
    }
    
    for (int i = 0; i < n; i++){
        if (visited[i] == 0) dfs(i);
    }
    
    for (int i = 0; i < n; i++){
        cout << i+1 << " " << d[i] << " " << f[i] << endl;
    }
    
    
}

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

vector<vector<int> > list(100);
vector<vector<int> > timed(100);
int times;
void dfs(int now){
	if(!timed[now].empty())	return;
	timed[now].push_back(times++);
	for(int i=0;i<(int)list[now].size();i++){
		dfs(list[now][i]);
	}
	timed[now].push_back(times++);
}

int main(){
	int n;	cin>>n;
	int id,num,ne;
	for(int i=0;i<n;i++){
		cin>>id>>num;
		id--;
		for(int j=0;j<num;j++){
			cin>>ne;
			list[id].push_back(ne-1);
		}
	}
	times=1;
	for(int i=0;i<n;i++){
		if(timed[i].empty())	dfs(i);
	}
	for(int i=0;i<n;i++){
		cout<<i+1;
		for(int j=0;j<(int)timed[i].size();j++){
			cout<<" "<<timed[i][j];
		}
		cout<<endl;
	}
	return 0;
}