Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

var infty = 1000000000

type nodeKey int

type DirectedGraphNode struct {
	key       nodeKey
	adjacents []*DirectedGraphNode
	visited   bool
	d         int
	f         int
	parent    *DirectedGraphNode
}

type DirectedGraph struct {
	nodes []*DirectedGraphNode
}

func (g *DirectedGraph) setAdjacency(l, r nodeKey) {
	g.nodes[l].adjacents = append(g.nodes[l].adjacents, g.nodes[r])
}

func newDirectedGraph(nNodes int) *DirectedGraph {
	graph := DirectedGraph{}
	graph.nodes = make([]*DirectedGraphNode, nNodes)
	for iNodes := 0; iNodes < nNodes; iNodes++ {
		graph.nodes[iNodes] = &DirectedGraphNode{}
		graph.nodes[iNodes].key = nodeKey(iNodes)

		graph.nodes[iNodes].visited = false
		graph.nodes[iNodes].d = infty
		graph.nodes[iNodes].f = infty
		graph.nodes[iNodes].parent = nil
	}
	return &graph
}

type QueueEntry struct {
	node *DirectedGraphNode
	next *QueueEntry
}

type Queue struct {
	head, tail *QueueEntry
}

func (q *Queue) enqueue(node *DirectedGraphNode) {
	entry := QueueEntry{}
	entry.node = node

	if q.tail == nil {
		q.head = &entry
		q.tail = &entry
		return
	}

	q.tail.next = &entry
	q.tail = q.tail.next
}

func (q *Queue) dequeue() *QueueEntry {
	if q.head == nil {
		return nil
	}
	poped := q.head
	q.head = q.head.next
	if q.head == nil {
		q.tail = nil
	}
	return poped
}

func (q *Queue) isEmpty() bool {
	return q.head == nil
}

var time = 0

func fillDistancesByDepthFirstSearch(g *DirectedGraph) {
	for _, u := range g.nodes[1:] {
		if !u.visited {
			dfsVisit(g, u)
		}
	}
}

func dfsVisit(g *DirectedGraph, u *DirectedGraphNode) {
	time++
	u.d = time

	u.visited = true
	for _, v := range u.adjacents {
		if !v.visited {
			v.parent = u
			dfsVisit(g, v)
		}
	}
	time++
	u.f = time
}

func main() {
	scanner.Split(bufio.ScanWords)

	nNodes := nextInt()
	g := newDirectedGraph(nNodes + 1)

	for iNode := 0; iNode < nNodes; iNode++ {
		nodeKeyLeft := nodeKey(nextInt())
		nAdj := nextInt()
		for iAdj := 0; iAdj < nAdj; iAdj++ {
			nodeKeyRight := nodeKey(nextInt())
			g.setAdjacency(nodeKeyLeft, nodeKeyRight)
		}
	}

	fillDistancesByDepthFirstSearch(g)

	for iNode := 1; iNode <= nNodes; iNode++ {
		node := g.nodes[iNode]
		fmt.Println(node.key, node.d, node.f)
	}
}

C++: #include <iostream>
#include <vector>
#include <string>

using namespace std;

int n;
vector<vector<int>> g; 
int timeT = 0;
vector<int> d, f;
 
void dfs(int node){
    timeT++;

    if(d[node] == 0){
        d[node] = timeT;
    }

    for(auto next : g[node]){
        if(d[next] == 0){
            dfs(next);
        }
    }
    
    timeT++;
    if(f[node] == 0){
        f[node] = timeT;
    }
    return;
}
    
int main(){
    
    cin >> n;

    d.assign(n + 1, 0);
    f.assign(n + 1, 0);

    g.assign(n + 1, vector<int>());

    for(int i = 0; i < n; i++)
    {
        int nod, numOut;
        cin  >> nod >> numOut;
        for(int j = 0; j < numOut; j++)
        {
            int temp;
            cin >> temp;
            g[nod].push_back(temp);
        }
    }
    
    dfs(1);

    for(int i = 1; i <= n; i++)
    {
        cout << i << " " << d[i] << " " << f[i] << endl;
    }
    

    return 0;
}

C++: // ALDS1_11_B.cpp
// Graph I - Depth First Search

#include <iostream>
#include <vector>
#include <cstdio>
using namespace std;

struct Vertex
{
    int id;
    vector<int> adjList;
    int d = 0;
    int f = 0;
};

int cnt = 0;

void dfs(vector<Vertex> &V, int n, int i)
{
    if (V[i].d != 0 && V[i].f != 0)
        return;
    int len = V[i].adjList.size();
    V[i].d = ++cnt;

    for (int j = 0; j < len; j++) {
        int next = V[i].adjList[j];
        if (V[next].d == 0) {
            // V[next].d = ++cnt;
            dfs(V, n, next);
            //V[next].f = ++cnt;
        }
    }
    V[i].f = ++cnt;
}

int main()
{
    int n;
    cin >> n;
    vector<Vertex> V(n);
    int id;
    int num;
    for (int i = 0; i < n; i++) {
        cin >> id >> num;
        V[id-1].id = id-1;
        int tmp;
        for (int j = 0; j < num; j++) {
            cin >> tmp;
            V[id-1].adjList.push_back(tmp-1);
        }
    }
    dfs(V, n, 0);
    for (int i = 0; i < n; i++) {
        printf("%d %d %d\n", i + 1, V[i].d, V[i].f);
    }
    return 0;
}

C++: #include <stdio.h>
#define REP(i,n) for(int i=0;i<n;i++)
#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2
int n,M[N][N]={0};
int color[N]={WHITE},D[N],F[N],tt=0;
void DFS_VISIT(int u){
  int v;
  color[u]=GRAY;
  D[u]=++tt;
  REP(v,n){
    if(M[u][v]==0) continue;
    if(color[v]==WHITE) DFS_VISIT(v);
  }
  color[u]=BLACK;
  F[u]=++tt;
}
void DFS(){
  int u;
  REP(u,n) if(color[u]==WHITE) DFS_VISIT(u);
  REP(u,n) printf("%d %d %d\n",u+1,D[u],F[u]);
}
int main(){
  int u,v,k;
  scanf("%d",&n);
  REP(i,n){
    scanf("%d %d",&u,&k);
    u--;
    REP(j,k){
      scanf("%d",&v);
      M[u][--v];
    }
  }
  DFS();
  return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;
typedef pair<int, int> P;

int n, u, k, v, t = 0, G[110][110], used[110];
P p[110];

void dfs(int u) {
    used[u] = 1;
    p[u].first = ++t;
    for (int i = 1; i <= n; i++) {
        if (!G[u][i] || used[i]) continue;
        used[i] = 1;
        dfs(i);
    }
    p[u].second = ++t;
}

int main(void) {
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> u >> k;
        for (int j = 0; j < k; j++) {
            cin >> v;
            G[u][v] = 1;
        }
    }

    for (int i = 1; i <= n; i++) {
        if (used[i]) continue;
        dfs(i);
    }

    for (int i = 1; i <= n; i++)
        cout << i << " " << p[i].first << " " << p[i].second << endl;

    return 0;
}

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

int r[101][101];
int d[101], f[101], num, visit[100]={0}, p=1;

void dfs(int n){
    if(visit[n]!=1){
        visit[n] = 1;
        d[n] = p++;
        for(int i=1; i<=num; i++)
            if(r[n][i]) dfs(i);
        f[n] = p++;
    }
}

int main(void){
    int u, k, v;
    cin >> num;
    for(int i=1; i<=num; i++){
        cin >> u >> k;
        for(int j=1; j<=k; j++){
            cin >> v;
            r[u][v]=1;
        }
    }
    for(int i=1; i<=num; i++){
        if(visit[i]!=1) dfs(i);
    }
    for(int i=1; i<=num; i++)
        cout << i << " " << d[i] << " " << f[i] << endl;
    return 0;
}