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()
}

Python: def visit(u):
    global visit_color, d, f, t
    color[u] = GRAY
    d[u] += t
    t += 1
    for v in range(n):
        if (M[u][v] == 0):
            continue
        else:
            if (color[v] == WHITE):
                visit(v)
    color[u] = BLACK
    f[u] = t
    t += 1

n = int(input())
M = [[False for i in range(n)] for j in range(n)]
for i in range(n):
    tmp = list(map(int, input().split()))
    for j in range(tmp[1]):
        M[tmp[0]-1][tmp[j+2]-1] = True

WHITE = 0
GRAY = 1
BLACK = 2
color = [WHITE for i in range(n)]
d, f = [0 for i in range(n)]
t = 1

for u in range(n):
    if (color[u] == WHITE):
        visit(u)
for u in range(n):
    print(str(u+1), str(d[u]), str(f[u]), sep = " ")

Python: n = int(input())
G = []
checked = [False for i in range(n + 1)]
d = [0 for i in range(n + 1)]
f = [0 for i in range(n + 1)]
G.append([])
for i in range(n):
    u, k, *v = map(int, input().split())
    G.append(v)

timestamp = 1

def dfs(id):
    global timestamp

    checked[id] = True
    d[id] = timestamp
    timestamp += 1
    for v in G[id]:
        if not checked[v]:
            dfs(v)
    f[id] = timestamp
    timestamp += 1

dfs(1)

for i in range(1, n + 1):
    print("{0} {1} {2}".format(i, d[i], f[i]))

Python: # coding: utf-8
import itertools
import math
import bisect

class Node:
    def __init__(self, id, next, rest):
        self.id = id
        self.before = None
        self.next = next
        self.rest = rest
        self.d = None
        self.f = None

    def update_next(self):
        self.next = first(self.rest)
        self.rest = rest(self.rest)


N = int(input())
graph = []
for _ in range(N):
    l = list(map(int, input().split(" ")))
    id = l[0]
    if l[1] != 0:
        next = l[2]
    else:
        next = None
    if l[1] >= 2:
        rest = l[3:]
    else:
        rest = []
    graph.append(Node(l[0], next, rest))

def first(l):
    if l==None:
        return None
    if len(l) == 0:
        return None
    else:
        return l[0]

def rest(l):
    if l == None:
        return None
    if len(l) >= 2:
        return l[1:]
    else:
        return None

def dfs(graph):
    stack = [graph[0]]
    stack[-1].d = 1
    tansakuzumi = [1]
    mitansaku = list(range(1, len(graph)+1))
    res_graph = []
    t = 2
    while len(stack) != 0:
        tansakuzumi.append(stack[-1].id)
        if stack[-1].id in mitansaku:
            mitansaku.remove(stack[-1].id)
        if stack[-1].next == None:
            stack[-1].f = t
            res_graph.append(stack.pop())
            t += 1
        elif stack[-1].next in tansakuzumi:
            stack[-1].update_next()
        else:
            stack.append(graph[stack[-1].next-1])
            stack[-2].update_next()
            stack[-1].d = t
            t += 1
        if len(stack) == 0 and len(mitansaku) >= 1:
            stack.append(graph[mitansaku[0]-1])
            stack[-1].d = t
            t += 1
    return res_graph




res_graph = dfs(graph)

res_graph.sort(key=lambda x: x.id)

for n in res_graph:
    print("{} {} {}".format(n.id, n.d, n.f))

Python: def dfs(v, cnt):
    D[v] = cnt
    cnt += 1
    for c in edge[v]:
        if D[c] == -1:
            cnt = dfs(c, cnt)
    F[v] = cnt
    cnt += 1
    return cnt


V = int(input())
edge = [[] for _ in range(V)]
for _ in range(V):
    u, _, *v = map(lambda x: int(x)-1, input().split())
    edge[u] = sorted(v)
D, F = [-1] * V, [-1] * V
_ = dfs(0, 1)
for i, (d, f) in enumerate(zip(D, F)):
    print(i, d, f)

Python: n = int(input())
a = [[0]*n for i in range(n)]
  
for i in range(n):
    v = list(map(int, input().split()))
    u = v[0]
    k = v[1]
    for j in range(k):
        a[u - 1][v[2 + j] - 1] = 1

d = [0] * n
f = [0] * n
isDiscovered = [False] * n
time_stamp = 0

def dfs(x):
    global time_stamp
    isDiscovered [x] = True
    time_stamp = time_stamp + 1
    d[x] = time_stamp
    for i in range(n):
        if a[x][i] == 1 and isDiscovered[i] == False:
            dfs(i)
    time_stamp = time_stamp + 1
    f[x] = time_stamp

for i in range(n):
    if isDiscovered[i] == False:
        dfs(i)

for i in rane(n):
    print(i+1, d[i], f[i])

Python: from sys import stdin
input = stdin.readline

N = int(input())
WHITE = 0
GRAY = 1
BLACK = 2

M = [[0]*N for _ in range(N)]
color = [WHITE]*N  # colorの初期化は最初に行っておく。
d = [0]*N
f = [0]*N

def dfs_visit(u):
    global tt
    color[u] = GRAY
    tt += 1
    d[u] = tt # 最初の訪問
    for v in range(N):
        if M[u][v] == 0:
            continue
        if color[v] == WHITE:
            dfs_visit(v)
    color[u] = BLACK
    tt += 1
    f[u] = tt # 訪問の完了

def dfs():
    global tt
    tt = 0

    for u in range(N):
        if color[u] == WHITE:
            # 未訪問のuを始点として深さ優先探索
            dfs_visit(u)
    for u in range(N):
        print(str(u+1) + ' ' + str(d[u]) + ' ' + str(f[u]))
for _ in range(N):
    u, k, *vv = input().split()
    u = int(u)-1  # 0オリジンにする
    k = int(k)    # kは使わない
    for v in vv:
        v = int(v)-1
        M[u][v] = 1
dfs()