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

WHITE = 0
GRAY = 1
BLACK = 2
color = [WHITE for _ in range(n)]
d = [0 for _ in range(n)]
f = [0 for _ in range(n)]
time = 1

def dfs(u):
    global dfs_color, d, f, time
    color[u] = GRAY
    d[u] += time
    time += 1
    for v in range(n):
        if A[u][v]:
            if color[v] == WHITE:
                dfs(v)
        else:
            continue
    color[u] = BLACK
    f[u] = time
    time += 1 

for u in range(n):
    if color[u] == WHITE:
        dfs(u)

for i in range(n):
    print(str(i+1) + ' ' + str(d[i]) + ' ' + str(f[i]) )

Python: n = int(input())
graph = {}
for _ in range(n):
  i = list(map(int,input().split()))
  graph[i[0]] = i[2:]

first = {i:0 for i in range(1,n+1)}
last = {i:0 for i in range(1,n+1)}
seen = set()
time = 1

def dfs(v):
  global time
  seen.add(v)
  first[v] = time
  time += 1
  for nxt in graph[v]:
    if nxt in seen:
      continue
    dfs(nxt)
  last[v] = time
  time += 1

for i in range(1,n+1):
  if i not in seen:
    dfs(i)
  
for i in range(1,n+1):
  print(i, first[i], last[i])

Python: import sys

def debug(x, table):
    for name, val in table.items():
        if x is val:
            print('DEBUG:{} -> {}'.format(name, val), file=sys.stderr)
            return None

time = 0

def dfs(u, adj, d, f, sumi):
    global time
    time += 1
    d[u] = time

    for v in adj[u]:
        if v not in sumi:
            dfs(v, adj, d, f, sumi)
        sumi.add(v)

    time += 1

    f[u] = time


def solve():
    n = int(input())
    adj = [None] * n

    for i in range(n):
        u, k, *vs = [int(j) - 1 for j in input().split()]
        # debug(vs, locals())
        adj[u] = vs

    # debug(adj, locals())
    
    d = [0] * n
    f = [0] * n
    sumi = {0}

    dfs(0, adj, d, f, sumi)

    for i in range(n):
        print(i, d[i], f[i])

    pass

if __name__ == '__main__':
    solve()

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

import sys

WHITE, GRAY, BLACK = 0, 1, 2


def generate_adj(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(start_node_index):
    # init the first node
    v_index = int(start_node_index)
    vertex_visit_stack.append(v_index)
    vertex_color_list[v_index] = GRAY
    time = 1
    vertex_d_time[v_index] += time
    # init end
    while len(vertex_visit_stack) > 1:
        current_vertex = vertex_visit_stack[-1]
        try:
            next_vertex = adj_matrix[current_vertex - 1].index(1) + 1
        except ValueError:
            # print('err')
            vertex_visit_stack.pop()
            vertex_color_list[current_vertex] = BLACK
            time += 1
            vertex_f_time[current_vertex] += time
        else:
            if vertex_color_list[next_vertex] == WHITE:
                # print('w2g', current_vertex, next_vertex, vertex_color_list[next_vertex])
                vertex_color_list[next_vertex] = GRAY
                time += 1
                vertex_d_time[next_vertex] += time
                vertex_visit_stack.append(next_vertex)
                # node A to B only visit once
                adj_matrix[current_vertex - 1][next_vertex - 1] = 0
            else:
                time += 1
                vertex_f_time[current_vertex] += time
                vertex_visit_stack.pop()
    return None


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

    vertex_visit_stack = [-1]
    vertex_color_list = [WHITE] * (vertex_num + 1)
    vertex_d_time, vertex_f_time = [0] * (vertex_num + 1), [0] * (vertex_num + 1)
    adj_matrix = generate_adj(vertex_info)

    graph_dfs(start_node_index=1)
    for i in range(vertex_num):
        print(i + 1, vertex_d_time[i + 1], vertex_f_time[i + 1])

Python: n = int(input())

graph = []
for _ in range(n):
    tmp = list(map(int, input().split()))
    if tmp[1] == 0:
        graph.append([])
    else:
        graph.append(tmp[2:])
#print(graph)

seen = [0]*n
to_do = []
in_list = [0]*n
out_list = [0]*n
count = 0

def dfs(v):
    #print(v)
    global count
    if seen[v] == 0:
        seen[v] = 1
        count += 1
        in_list[v] = count
        to_do = graph[v]
        #print(in_list)
        #print(to_do)
        if len(to_do) > 0:
            for i in to_do:
                dfs(i-1)
        count += 1
        out_list[v] = count
        #print(out_list)
while True:
    if 0 in seen:
        k = seen.index(0)
        dfs(k)
    else:
        break

for i in range(n):
    print("{} {} {}".format(i+1,in_list[i],out_list[i]))