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

// ------ Class ------ //
class Graph1 {
public:
	// ------ Variables ------ //
	static const int INF = 1000000000;
	int V, E; vector<vector<int> > G;

	// ------ Constructors ------ //
	Graph1() : V(0), E(0), G(vector<vector<int> >()) {}
	Graph1(int v) : V(v), E(0), G(vector<vector<int> >(v)) {}
	Graph1(vector<vector<int> > g) : V(g.size()), G(g) { for (int i = 0; i < g.size(); i++) E += g[i].size(); }

	// ------ Basic Functions ------ //
	int size() { return V; }
	void add1(int v1, int v2) { G[v1].push_back(v2); E++; }
	void add2(int v1, int v2) { add1(v1, v2); add1(v2, v1); }

	// ------ Operators ------ //
	friend bool operator==(const Graph1& g1, const Graph1& g2) { return g1.G == g2.G; }
	friend bool operator!=(const Graph1& g1, const Graph1& g2) { return g1.G != g2.G; }
	vector<int> operator[](int x) { return G[x]; }
};

// ------ Main ------ //
int n, u, k, v, t, d[100][2];
void rec(int pos) {
	for(int i = 0; i < g[i].size(); i++) {
		if(!d[g[i][j]][0]) {
			d[g[i][j]][0] = ++t;
			rec(g[i][j]);
			d[g[i][j]][1] = ++t;
		}
	}
}
int main() {
	cin >> n; Graph1 g(n);
	for(int i = 0; i < n; i++) {
		cin >> u >> k;
		for(int j = 0; j < k; j++) cin >> v, g.add1(u - 1, v - 1);
	}
	for(int i = 0; i < n; i++) cout << i + 1 << ' ' << d[i][0] << ' ' << d[i][1] << endl;
}

C++: #define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <cstdio>
#include <stack>
using namespace std;
stack<int> st;
int  v[102][101], n;
int  tim[102][2];
int ct = 1;
int go[102];
inline void search(int t) {
	if(!tim[t][0]) tim[t][0] = ct++;
	go[t] = 1;
	int tf = 0;
	for (int a = 1; a <= n; a++) {
		if (v[t][a]) {
			st.push(a);
			for (int i = 1; i <= n; i++) {
				v[i][a] = 0;
			}
			search(st.top());
			tf = 1;
		}
	}
		
	if(!tf) {
		st.pop();
		tim[t][1] = ct++;
		if(!st.empty()) search(st.top());
	}
}
int main() {

	st.push(1);
	int u, k, s;
	cin >> n;
	for (int i = 0; i <= n; i++) {
		for (int j = 0; j <= n; j++) {
			v[i][j] = 0;
		}
	}
	for (int i = 0; i < n; i++) {
		cin >> u;
		cin >> k;
		for (int j = 0; j < k; j++) {
			cin >> s;
			v[u][s] = 1;
		}
	}
	search(1);
	for (int i = 2; i <= n; i++) {
		if (!go[i]) {
			st.push(i);
			search(i);
	}
}
	for (int i = 1; i <= n; i++) {
		cout << i << " " << tim[i][0] << " " << tim[i][1] << endl;
	}
	return 0;
}

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

using namespace std;

struct Edge
{
	int to;
};

vector<vector<int>> DFS(vector<vector<Edge>>& G)
{
	int timecounter = 0;
	vector<vector<int>> result;
	result = vector<vector<int>>(2, vector<int>(G.size(), 0));
	vector<int> prev(G.size(),0);
	
	for(int i = 0; i < G.size(); i++){
		int next = i + 1;
		while(result[1][i] == 0){
			int tmp;
			if(result[0][next - 1] == 0){
				timecounter += 1;	
				result[0][next - 1] = timecounter;
			}

			if(G[next - 1].empty()){
				if(result[1][next - 1] == 0){
					timecounter += 1;
					result[1][next - 1] = timecounter;
				}
				next = prev[next - 1];
			}else{
				tmp = G[next - 1].begin()->to;
				G[next - 1].erase(G[next - 1].begin());
				if(tmp != next)
					prev[tmp - 1] = next;
				next = tmp;
			}
		}
	}
	return result;
}

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

	vector<vector<Edge>> AdjList(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;
			AdjList[i].push_back(Edge{v});
		}
	}

	vector<vector<int>> timestump = DFS(AdjList);
	
	for(int i = 0; i < AdjList.size(); i++){
		cout << i + 1 << " " << timestump[0][i] << " " << timestump[1][i] << endl;
	}
	return 0;
}

C++: #include <stdio.h>
#include <iostream>
#include <stack>
#include <string>
using namespace std;

#define NUM 100
int node_num;
int V[NUM + 1][NUM + 1];
int d[NUM + 1];
int f[NUM + 1];
string color[NUM + 1];
int t;
int pos;
stack<int> s;

void createAdj(int n){
    for(int i = 1; i < NUM; i++){
        for(int j = 1; j < NUM; j++){
            V[i][j] = 0;
        }
    }

    for(int i = 0; i < n; i++){
        int num1;
        scanf("%d", &num1);

        int n;
        scanf("%d", &n);

        int num2;
        for(int j = 0; j < n; j++){
            scanf("%d", &num2);
            V[num1][num2] = 1;
        }
    }
}

int search(int n){
    for(int i = 1; i <= node_num; i++) {
        if(V[n][i] == 1 && color[i] == "white")
            return i;
        if(V[i][n] == 1 && color[i] == "white")
            return i;
    }
    return -1;
}

void dfs_init(){
    t = 0;
    for(int i = 0; i < NUM; i++){
        color[i] = "white";
    }
}

void dfs(){
    s.push(1);
    pos = 1;
    t++;
    color[1] = "grey";
    d[1] = t;

    while(s.size()){
        int u = s.top();
        int next_node = search(u);
        if(next_node != -1){
            pos = next_node;
            s.push(next_node);
            pos = next_node;
            t++;
            color[next_node] = "grey";
            d[next_node] = t;
        }else{
            s.pop();
            color[u] = "black";
            t++;
            f[u] = t;
        }
    }
}

void print(){
    for(int i = 1; i <= node_num; i++){
        printf("%d %d %d\n", i, d[i], f[i]);
    }
}

int main(void){
    scanf("%d", &node_num);
    createAdj(node_num);

    dfs_init();
    dfs();

    print();
}