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) isVisited() bool {
	return v.firstVisitAt > 0
}

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	currentVertex := &vertices[currentId-1]
	if currentVertex.isVisited() {
		return timestamp
	}
	timestamp = timestamp + 1
	currentVertex.firstVisitAt = timestamp
	for _, adjId := range currentVertex.adjs {
		timestamp = dfs(adjId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

func solveDfs(vertices []vertex) {
	timestamp := 0
	for {
		vid := vertexId(-1)
		for i := 0; i < len(vertices); i++ {
			if !vertices[i].isVisited() {
				vid = vertexId(i+1)
				break
			}
		}
		if vid > 0 {
			timestamp = dfs(vid, timestamp, vertices)
		} else {
			break
		}
	}
}

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)
	}

	solveDfs(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))
}

Python: G = {}
for _ in range(int(input())):
  x = list(map(int, input().split()))
  G[x[0]] = sorted(x[2:])

t = 1
stack = [1]
timestamp = {1:[t]}

while len(stack) > 0:
  t += 1
  v = stack[-1]

  while len(G[v]) > 0:
    v = G[v].pop(0)
    if v in timestamp: continue
    stack.append(v)
    timestamp[v] = [t]
    break
  else:
    v = stack.pop()
    timestamp[v].append(t)

for i in timestamp:
  print(i, *timestamp[i])

Python: import sys

time = 0
def dfs(u):
    global time
    flag_list[u] = 1
    time += 1
    d_list[u] = time
    for v in range(n):
        if m_list[u][v] == 1 and flag_list[v] == 0:
            dfs(v)
    flag_list[u] = 2
    time += 1
    f_list[u] = time


input = sys.stdin.readline
n = int(input())
m_list = [[0]*n for _ in range(n)]
for _ in range(n):
    input_list = list(map(int, input().split()))
    index = input_list[0] - 1
    if input_list[1] > 0:
        for a in input_list[2:]:
            m_list[index][a-1] = 1
    
d_list = [0]*n
f_list = [0]*n
flag_list = [0]*n # 0: 未到達, 1: 処理中, 2: 完了
for i in range(n):
    if flag_list[i] == 0:
        dfs(i)

for i in range(n):
    print(i+1, d_list[i], f_list[i])

Python: G = {}
N = int(input())
for _ in range(N):
    L = list(map(int, input().split()))
    G[L[0]] = L[2:]

# print(G)
d = [-1] * N
f = [-1] * N
q = [1]
visited = [False] * N

time = 1


def dfs(v):
    global time
    visited[v-1] = True

    for nv in G[v]:
        if d[nv-1] < 0:
            d[nv-1] = time
            time += 1
        if not visited[nv-1]:
            dfs(nv)

    f[v-1] = time
    time += 1


for i in range(1, N+1):
    if not visited[i-1]:
        d[i-1] = time
        time += 1
        dfs(i)

for i in range(N):
    print(i+1, d[i], f[i])

Python: import math
import copy
import sys
import fractions
# import numpy as np
# import statistics
import decimal
import heapq
import collections
import itertools
import bisect


# from operator import mul

# sys.setrecursionlimit(100001)


# input = sys.stdin.readline
# sys.setrecursionlimit(10**6)

# ===FUNCTION===

def getInputIntList():
    outputDataList = []
    inputData = input().split()
    outputDataList = [int(n) for n in inputData]

    return outputDataList


def getSomeInputInt(n):
    outputDataList = []
    for i in range(n):
        inputData = int(input())
        outputDataList.append(inputData)

    return outputDataList


def getSomeInputListInt(n):
    inputDataList = []
    outputDataList = []
    for i in range(n):
        inputData = input().split()
        inputDataList = [int(n) - 1 for n in inputData]
        outputDataList.append(inputDataList)

    return outputDataList


# ===CODE===

n = int(input())

data = getSomeInputListInt(n)

ans = [[] for _ in range(n)]

edge = []
for d in data:
    edge.append(d[2:])


def dfs(i, cnt):
    if len(ans[i]) > 0:
        return cnt

    cnt += 1

    ans[i].append(cnt)
    for j in range(len(edge[i])):
        cnt = dfs(edge[i][j], cnt)

    cnt += 1
    ans[i].append(cnt)

    return cnt

tmp = 0
for i in range(n):
    tmp = dfs(i, tmp)

for i in range(n):
    print(i + 1, *ans[i], sep=" ")

Python: class Node:
    def __init__(self, data):
        self.data = data
        self.neighbors = list()
        self.find_time = 0
        self.end_time = 0

N = int(input())
work_id = 0
nodes = list()
nodes.append(Node(0))


for _ in range(N):
    tmp_list = list( map(int, input().split()) )
    node = Node(tmp_list[0])
    for i in range(tmp_list[1]):
        node.neighbors.append(tmp_list[i+2])
    nodes.append(node)
    nodes[0].neighbors.append(node.data)

# for node in nodes:
#     print(node.data, ":", node.neighbors)


def search(node):
    global work_id

    if node.find_time != 0:
        return
    
    if node.data != 0:
        work_id += 1
        node.find_time = work_id

    if len(node.neighbors) > 0:
        for neighbor in node.neighbors:
            search(nodes[neighbor])
    
    if node.data != 0:
        work_id += 1
        node.end_time = work_id

search(nodes[0])

for node in nodes:
    if node.data == 0: continue
    print(node.data, node.find_time, node.end_time)

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

"""

input:
6
1 2 2 3
2 2 3 4
3 1 5
4 1 6
5 1 6
6 0

output:
1 1 12
2 2 11
3 3 8
4 9 10
5 4 7
6 5 6

"""
import sys

UNVISITED, VISITED_IN_STACK, POPPED_OUT = 0, 1, 2


def dfs(v_init):
    global timer

    # init the first node of overall graph iterations(times >= 1)
    stack = list()
    stack.append(v_init)
    d_time[v_init] += timer
    # init end

    while stack:
        current = stack[-1]
        v_table = adj_table[current]
        visited[current] = VISITED_IN_STACK
        # if adj is None, current's adj(s) have been all visited
        adj = v_table.pop() if v_table else None

        if adj:
            if visited[adj] is UNVISITED:
                visited[adj] = VISITED_IN_STACK
                timer += 1
                d_time[adj] += timer
                stack.append(adj)
        else:
            stack.pop()
            visited[current] = POPPED_OUT
            timer += 1
            f_time[current] += timer

    return None


def dfs_init():
    global timer
    for v in range(v_num):
        if visited[v + 1] == UNVISITED:
            timer += 1
            dfs(v + 1)


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    v_num = int(_input[0])
    vertices = map(lambda x: x.split(), _input[1:])

    # config length = (v_num + 1)
    # stack = []
    visited = [UNVISITED] * (v_num + 1)
    d_time, f_time = ([0] * (v_num + 1) for _ in range(2))
    adj_table = tuple([] for _ in range(v_num + 1))
    for v_info in vertices:
        v_index, adj_num, *adj_list = map(int, v_info)
        # assert len(adj_list) == adj_num
        adj_table[v_index].extend(sorted(adj_list, reverse=True))

    # timing start from 1
    timer = 0
    dfs_init()

    for index, time_info in enumerate(zip(d_time[1:], f_time[1:]), 1):
        print(index, *time_info)