Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	G := make([][]int, N)
	for i := 0; i < N; i++ {
		u, k := sc.nextInt()-1, sc.nextInt()
		for j := 0; j < k; j++ {
			G[u] = append(G[u], sc.nextInt()-1)
		}
	}
	ans := make([][2]int, N)
	time := 0
	found := make(map[int]bool)
	var dfs func(cur int)
	dfs = func(cur int) {
		time++
		ans[cur][0] = time
		found[cur] = true
		for i := 0; i < len(G[cur]); i++ {
			next := G[cur][i]
			if !found[next] {
				dfs(G[cur][i])
			}
		}
		time++
		ans[cur][1] = time
	}
	for i := 0; i < N; i++ {
		if !found[i] {
			dfs(i)
		}
	}

	for i := 0; i < N; i++ {
		fmt.Fprint(wtr, i+1)
		for j := 0; j < 2; j++ {
			fmt.Fprint(wtr, " ")
			fmt.Fprint(wtr, ans[i][j])
		}
		fmt.Fprintln(wtr)
	}
	wtr.Flush()
}

C++: #include <iostream>
#include <set>
#include <vector>
#include <queue>
#include <stack>
#include <utility>

using namespace std;

typedef long long signed int ll;

constexpr ll NIL = -20000000000;

int g[101][101],n,d[101],f[101];

int main() {
    cin >> n;
    for(int i = 0;i < n;i++) {
        int u,k,v;
        cin >> u >> k;
        for(int j = 0;j < k;j++) {
            cin >> v;
            g[u][v]++;
        }
    }
    stack<int> dfs;
    int time = 1;
    dfs.push(1);
    d[1] = time;
    while(!dfs.empty()){
        int u = dfs.top();
        bool flag = false;
        for(int i = 1;i <= n;i++){
            if(g[u][i] && d[i] == 0) {
                dfs.push(i);
                time++;
                d[i] = time;
                flag = true;
            }
        }
        if(!flag){
            dfs.pop();
            time++;
            f[u] = time;
        }
    }
    for(int i = 1;i <=n;i++) {
        cout << i << " " << d[i] << " " << f[i] <<endl;
    }
}

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

int G[101][102];
int found[101];
int comp[101];   // complete.
int t;  // time.

typedef struct box{ int val; box* next; } box_t;  // stack.

box_t* init()
{
    box_t* head = new box_t;
    head->val = -1;
    head->next = NULL;
    return head;
}

bool isEmpty(box_t* head){ return (head->next == NULL ? true : false); }

box_t* push(box_t* head, int data)
{
    box_t* box = new box_t;
    box->val = data;
    box->next = head->next;
    head->next = box;
    return box;
}

int pop(box_t* head)
{
    if(isEmpty(head)){ return -1; }
    box_t* box = head->next;
    int val;
    head->next = box->next;
    val = box->val;
    delete box;
    return val;
}

int front(box_t* head)
{
    int val;
    if(isEmpty(head)){ return -1; }
    val = head->next->val;
    return val;
}

box_t* stack = init();

void search_loop(int i)
{
    int j, k;
    while(1){
        if(found[i] == 0){
            t++; found[i] = t;
            push(stack, i);
        }
        for(k = G[i][0]; G[i][k] != 0 && found[G[i][k]] != 0; k++);
        if(G[i][k] == 0){
            if(isEmpty(stack)){ return; }
            else{
                j = pop(stack);
                t++; comp[j] = t;
                i = front(stack);
            }
        }else{
            G[i][0] = k + 1;
            i = G[i][k];
        }
    };
    return;
}

int main()
{
    int n, i, j, a, b, e;
    cin >> n;
    for(i = 1; i <= n; i++){
        G[i][0] = 1;
        for(j = 1; j <= n + 1; j++){ G[i][j] = 0; } }

    for(i = 1; i <= n; i++){
        cin >> a >> e;
        for(j = 1; j <= e; j++){
            cin >> b; G[a][j] = b; } }  // adjacent representation.

    for(i = 1; i <= n; i++){ found[i] = 0; comp[i] = 0; }
    t = 0;
    while(1){
        for(i = 1; i <= n; i++){
            if(found[i] == 0) break;
        }
        if(i > n) break;
        search_loop(i);
    };

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

C++: #include <iostream>
#include <vector>
#define N 2000

using namespace std;
vector<vector<int> > pa;
vector<vector<int> > ch;
int first[N] = {0};
int second[N] = {0};
int timestamp = 0;
void dfs(int x) {
    if (ch[x].empty()) {
        return;
    } else {
        for (int i = 0; i < ch[x].size(); i++) {
            if (first[ch[x][i]] * second[ch[x][i]] == 0) {
                timestamp++;
                first[ch[x][i]] = timestamp;
                dfs(ch[x][i]);
                timestamp++;
                second[ch[x][i]] = timestamp;
            }
        }
        return;
    }
}
int main() {
    int n;
    cin >> n;
    int temp = n;
    pa.clear(); pa.resize(N + 5);
    ch.clear(); ch.resize(N + 5);
    while (temp--) {
        int u, k, v;
        cin >> u >> k;
        for (int i = 0; i < k; i++) {
            cin >> v;
            pa[v].push_back(u);
            ch[u].push_back(v);
        }
    }
    int an = 0;
    for (int i = 1; i <= n; i++) {
        if (pa[i].empty()) {
            an = i;
        } else {
            sort(pa[i].begin(), pa[i].end(), less<int>());
        }
        if (ch[i].empty()) {
            ;
        } else {
            sort(ch[i].begin(), ch[i].end());
        }
    }
    timestamp++;
    first[an] = timestamp;
    dfs(an);
    timestamp++;
    second[an] = timestamp;
    for (int i = 1; i <= n; i++) {
        cout << i << ' ' << first[i] << ' ' << second[i] << '\n';
    }
}