Go: package main

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

type TimeRecord struct {
	discoverTime int
	finishTime   int
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	timeRecordMap := make([]TimeRecord, n)
	childrenMap := make([][]int, n)
	for i := 1; i <= n; i++ {
		node, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		timeRecordMap[node-1] = TimeRecord{-1, -1}

		childNum, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		childrenMap[node-1] = make([]int, childNum)
		for j := 0; j < childNum; j++ {
			child, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			childrenMap[node-1][j] = child
		}
	}

	// TODO: always start with 1?
	timer := 1
	visit(1, &timer, childrenMap, timeRecordMap)
	for k, v := range timeRecordMap {
		fmt.Printf("%d %d %d\n", k+1, v.discoverTime, v.finishTime)
	}
}

func visit(currentNode int, timer *int, childrenMap [][]int, timeRecordMap []TimeRecord) {
	if timeRecordMap[currentNode-1].discoverTime > 0 {
		return
	}
	children := childrenMap[currentNode-1]
	timeRecordMap[currentNode-1] = TimeRecord{*timer, timeRecordMap[currentNode-1].finishTime}
	(*timer)++
	for i := 0; i < len(children); i++ {
		visit(children[i], timer, childrenMap, timeRecordMap)
	}
	timeRecordMap[currentNode-1] = TimeRecord{timeRecordMap[currentNode-1].discoverTime, *timer}
	(*timer)++
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

Python: from sys import stdin
n = int(stdin.readline())
M = [None]
M += [list(map(int, stdin.readline().split()[2:])) for i in range(n)]
sndf = [None]
sndf += [[False, i] for i in range(1, n + 1)]
tt = 0
def dfs(u):
    global tt
    sndf[u][0] = True
    tt += 1
    sndf[u].append(tt)
    for v in M[u]:
        if not sndf[v][0]:
            dfs(v)
    tt += 1
    sndf[u].append(tt)
for i in range(1, n + 1):
    if not sndf[i][0]:
        dfs(i)
    print(*sndf[i][1:])

Python: def depth(s, time):
    time += 1
    flag[s] = 1
    d[s] = t
    for i in range(1, n+1):
        if G[s][i] == 1:
            if flag[i] == 0:
                depth(i, time)
                t = f[i]
    f[s] = time + 1
 
n = int(raw_input())
G = [[0 for i in range(n+1)] for j in range(n+1)]
d = [0 for i in range(n+1)]
f = [0 for i in range(n+1)]
 
for i in range(n):
    v = map(int, raw_input().split())
    for j in range(v[1]):
        G[v[0]][v[2+j]] = 1
 
flag = [0 for i in range(n+1)]
for i in range(1, n+1):
    if flag[i] == 0:
        depth(i, max(f))
 
for i in range(1, n+1):
    print(str(i) + " " + str(d[i]) + " " + str(f[i]))

Python: # -*- coding: utf-8 -*-
"""
Created on Sun Jul  8 10:56:33 2018

@author: maezawa
"""
n = int(input())
adj = [[] for _ in range(n)]
d = [0 for _ in range(n)]
f = [0 for _ in range(n)]

for j in range(n):
    ain = list(map(int, input().split()))
    u = ain[0]
    k = ain[1]
    for i in range(k):
        adj[u-1].append(ain[i+2]-1)
    adj[u-1].sort()
    #print(*adj[u-1])

t = 1

for j in range(n):
    if d[j] == 0:
        stack = [j]

    while stack:
        #print(stack)
        current = stack[-1]
        if d[current] == 0:
            d[current] = t
            t += 1
        flag = 0
        for k in adj[current]:
            if d[k] == 0:
                stack.append(k)
                flag = 1
                break
        if flag == 0:
            f[current] = t
            t += 1
            stack.pop()

    #print('current = {}, t = {}'.format(current, t))
    #print('stack', *stack)

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

Python: def get_unvisted_child(v, timestamp):
  while len(G[v]) > 0:
    c = G[v].pop(0)
    if not c in timestamp: return c
  return -1

def get_unvisited_node(G, timestamp):
  for v in sorted(G):
    if not v in timestamp: return v
  return -1

def dept_first_search(G):
  t = 1
  timestamp = {}
  stack = []

  v = get_unvisited_node(G, timestamp)
  while v > 0:
    stack.append(v)
    timestamp[v] = [t]
    t += 1

    while len(stack) > 0:
      v = stack[-1]
      c = get_unvisted_child(v, timestamp)
      if c > 0:
        #c = G[v].pop(0)
        stack.append(c)
        timestamp[c] = [t]
      else:
        timestamp[v].append(t)
        stack.pop()
      t += 1

    v = get_unvisited_node(G, timestamp)

  for v in sorted(timestamp):
    print(v, *timestamp[v])

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

dept_first_search(G)

Python: def d(u):
 global t
 C[u]=1;D[u]=t;t+=1
 for v in M[u]:v=int(v)-1;C[v]or d(v)
 F[u]=t;t+=1
N=int(input());R=range(N)
M=[input().split()[2:]for _ in R]
C,D,F=[0]*N,[0]*N,[0]*N
t=1
for i in R:C[i]or d(i)
for i in R:print(i+1,D[i],F[i])

Python: #!/usr/bin/env python3

import sys
import math
from bisect import bisect_right as br
from bisect import bisect_left as bl
sys.setrecursionlimit(2147483647)
from heapq import heappush, heappop,heappushpop
from collections import defaultdict
from itertools import accumulate
from collections import Counter
from collections import deque
from operator import itemgetter
from itertools import permutations
mod = 10**9 + 7
inf = float('inf')
def I(): return int(sys.stdin.readline())
def LI(): return list(map(int,sys.stdin.readline().split()))

cnt = 1
def dfs(x):
    global cnt
    if s[x] == None:
        s[x] = cnt
        cnt += 1
    for v in edges[x]:
        if s[v] == None:
            dfs(v)
    g[x] = cnt
    cnt += 1
    return 

n = I()
edges = [[] for _ in range(n)]
for i in range(n):
    edges[i] = list(map(lambda x:x-1,LI()[2:]))

s = [None]*n
g = [None]*n
for i in range(n):
    if s[i] == None:
        dfs(i)
for i in range(n):
    print(i+1,s[i],g[i])

Python: from typing import List


def dfs(adj_matrix: List[List[int]], vartex: int) -> int:
    global step
    global discover_times
    global finish_times
    if 0 != discover_times[vartex]:
        return 0
    discover_times[vartex] = step

    for col_idx in range(len(adj_matrix)):
        if (0 != adj_matrix[vartex][col_idx]) and (0 == discover_times[col_idx]):
            step += 1
            dfs(adj_matrix, col_idx)

    step += 1
    finish_times[vartex] = step

    return 1


if __name__ == "__main__":
    num_vertices = int(input())
    adj_matrix = [[0] * num_vertices for i in range(num_vertices)]

    for _ in range(num_vertices):
        vertex, _, *adjs = map(lambda x: int(x), input().split())
        for adj in adjs:
            adj_matrix[vertex - 1][adj - 1] = 1

    step = 1
    discover_times = [0] * num_vertices
    finish_times = [0] * num_vertices

    for vartex in range(num_vertices):
        if 1 == dfs(adj_matrix, vartex):
            step += 1

    for vertex, (d, f) in enumerate(zip(discover_times, finish_times)):
        print(f"{vertex + 1} {d} {f}")