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)
	}
}

Python: n = int(raw_input())

d = [0 for i in range(n)]
f = [0 for i in range(n)]
a = [[0 for i in range(n)] for j in range(n)]
st = [0 for i in range(n)]
time = [0]

def dfs_visit(s):
    st[s] = 1
    time[0] += 1
    d[s] = time[0]
    
    for k in range(n):  
      if a[s][k] == 1 and st[k] == 0:
          dfs_visit(k)
    st[s] == 2
    time[0] += 1
    f[s] = time[0]

def main():
    for s in range(n):
        if st[s] == 0:
            def_visit(s)
    for s in range(n):
        print(s+1,d[s],f[s])

Python: def dfs(num, lst, d, f, cnt):
    if d[num] != 0:
        return cnt - 1
    d[num] = cnt
    for n in lst[num]:
        cnt += 1
        cnt = dfs(n - 1, lst, d, f ,cnt)
    cnt += 1
    f[num] = cnt
    return cnt


n = int(input())
d = [0 for i in range(n)]
f = [0 for i in range(n)]
lst = []
for _ in range(n):
    n = list(map(int, input().split()))
    lst.append(n[2:])

cnt = 1
while 0 in d:
    num = d.index(0)
    cnt = dfs(num, lst, d, f, cnt) + 1

for i, j in enumerate(zip(d, f)):
    print(i + 1, j[0], j[1])

Python: #!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys

UNVISITED, VISITED_IN_STACK, POPPED_OUT = 0, 1, 2


def generate_adj_matrix(v_info):
    for v_detail in v_info:
        v_adj_list = v_detail[2:]
        # assert len(v_adj_list) == int(v_detail[1])
        for each in v_adj_list:
            init_adj_matrix[int(v_detail[0]) - 1][int(each) - 1] = 1
    return init_adj_matrix


def graph_dfs(v_init):
    global time

    # init the first node of overall graph iterations(times >= 1)
    vertices_visit_stack.append(v_init)
    vertices_status_list[v_init] = VISITED_IN_STACK
    vertices_d_time[v_init] += time
    # init end

    while len(vertices_visit_stack) > 1:
        current_vertex = vertices_visit_stack[-1]
        next_vertex = get_adj_vertices(vertex=current_vertex)

        if next_vertex:
            if vertices_status_list[next_vertex] is UNVISITED:
                vertices_status_list[next_vertex] = VISITED_IN_STACK
                time += 1
                vertices_d_time[next_vertex] += time
                vertices_visit_stack.append(next_vertex)
        else:
            vertices_visit_stack.pop()
            vertices_status_list[current_vertex] = POPPED_OUT
            time += 1
            vertices_f_time[current_vertex] += time

    return None


def get_adj_vertices(vertex):
    index = int(vertex) - 1
    for j in range(vertices_num):
        if adj_matrix[index][j]:
            adj_matrix[index][j] = 0
            return j + 1
    return None


def dfs_start():
    global time
    for i in range(vertices_num):
        if vertices_status_list[i + 1] == UNVISITED:
            # print('round: ', i + 1)
            graph_dfs(v_init=i + 1)
            time += 1


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    vertices_num = int(_input[0])
    vertices_info = list(map(lambda x: x.split(), _input[1:]))
    init_adj_matrix = tuple([[0] * vertices_num for _ in range(vertices_num)])
    # assert len(vertex_info) == vertex_num

    # config length = (vertex_num + 1)
    vertices_visit_stack = [-1]
    vertices_status_list = [UNVISITED] * vertices_num
    vertices_status_list.insert(0, -1)
    vertices_d_time, vertices_f_time = ([0] * (vertices_num + 1) for _ in range(2))

    adj_matrix = generate_adj_matrix(vertices_info)
    # timing start from 1
    time = 1
    dfs_start()
    for k in range(vertices_num):
        print(k + 1, vertices_d_time[k + 1], vertices_f_time[k + 1])

Python: from sys import stdin

d_num = int(stdin.readline().strip())

graph = [[] for _ in range(d_num+1)]
for _ in range(d_num):
    u, k, *neighbors = map(int, stdin.readline().split())
    for v in neighbors:
        graph[u].append(v)
        graph[v].append(u)

visited = set()
timestamps = [None for _ in range(d_num+1)]

def dfs(u, stmp):
    visited.add(u)
    entry = stmp

    stmp += 1
    for v in graph[u]:
        if v not in visited:
            stmp = dfs(v, stmp)

    timestamps[u] = entry, stmp
    return stmp+1

dfs(1, 1)

for num, (entry, leave) in enumerate(timestamps[1:], 1):
    print(num, entry, leave)

Python: #Boost Force  / Backtracking
import sys
input = sys.stdin.readline
d = []
f = []
time = 0
#ทำการ search
def search(r):
    global d,f,time,s
    if d[r] == 0:
        time += 1
        d[r] = time
    else:
        return
    for x in s[r]:
        search(x)
    time += 1
    f[r] = time


n = int(input()) #รับค่าจำนวน node ทั้งหมด
s = [[] for i in range(n+1)]
for _ in range(n):
    d = list(map(int,input().split())) #รับข้อมูลทีละบรรทัด split เก็บเป็น int
    #ตน d[0] คือ node ตน 1 คือ ดีกรี ตนตั้งแต่ 2ไป คือ vertex
    s[d[0]] = d[2:]

d = [0 for _ in range(n+1)]
f = [0 for _ in range(n+1)]

for i in range(1,n+1):
    if d[i] == 0:
        search(i)

#แสดง node เวลาที่เจอ และ เวลา finish
for i in range(1,n+1):
    print (i,d[i],f[i])