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: import sys
import itertools
# import numpy as np
import time
import math
 
sys.setrecursionlimit(10 ** 7)
 
from collections import defaultdict
 
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

N = int(input())

adj = [[] for _ in range(N)]

for i in range(N):
    line = list(map(int, input().split()))
    u = line[0] - 1
    if line[1] == 0:
        continue
    vs = line[2:]
    for v in vs:
        adj[u].append(v - 1)

d = [-1] * N
f = [-1] * N

def dfs(v, t):
    d[v] = t
    nx = t + 1
    for u in adj[v]:
        if d[u] > -1:
            continue
        nx = dfs(u, nx)
    f[v] = nx
    return f[v] + 1

nx = 1
for i in range(N):
    if d[i] > - 1:
        continue
    nx = dfs(i, nx)

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

Python: #!/usr/bin/env python
from __future__ import division, print_function
from sys import stdin


def walk(index, tm, L, d, f):
    tm += 1
    d[index] = tm
    for i in L[index]:
        if not d[i-1]:
            tm = walk(i-1, tm, L, d, f)
    tm += 1
    f[index] = tm
    return tm


def main():
    num = int(stdin.readline())

    L = []
    for _ in xrange(num):
        L.append([int(s) for s in stdin.readline().split()[2:]])

    d = [0] * num
    f = [0] * num
    tm = 0
    for i in xrange(num):
        if not d[i]:
            tm = walk(i, tm, L, d, f)

    for i in xrange(num):
        print(i+1, d[i], f[i])


main()

Python: n = int(input())
G = [[] for _ in range(n)]
u1 = 0
for _ in range(n):
    u, k, *v = [int(i) for i in input().split()]
    G[u - 1] = v
    if k != 0 and u1 == 0:
        u1 = u

time = 1
u = u1
D = []
F = []
out = [[i+1, 0, 0] for i in range(n)]
T = []
while True:
    if u not in D:
        out[u - 1][1] = time
        D.append(u)
        T.append(u)

    for f in F:
        if f in G[u - 1]:
            idx = G[u - 1].index(f)
            del G[u - 1][idx]

    if G[u - 1] == []:
        time += 1
        out[T.pop() - 1][2] = time
        F.append(u)
        if T == []:
            if len(D) == n:
                break
            else:
                for ni in range(n):
                    if ni + 1 not in D:
                        u = ni + 1
                        break
                time += 1
                continue
        else:
            u = T[-1]
    else:
        if G[u - 1][0] not in D:
            time += 1
        u = G[u - 1].pop(0)

for ni in range(n):
    print(*out[ni])

Python: class Vertex:
    _id = -1
    _children = []
    _visited = False
    _visited_time = 0
    _all_visited_time = 0

    def __init__(self, i, c):
        self._id = i
        self._children = c

    def getId(self):
        return self._id

    def getChildren(self):
        return self._children

    def isVisited(self):
        return self._visited

    def getVisitedTime(self):
        return self._visited_time

    def setVisitedTime(self, t):
        self._visited_time = t
        self._visited = True

    def getAllVisitedTime(self):
        return self._all_visited_time

    def setAllVisitedTime(self, t):
        self._all_visited_time = t

    def print(self):
        print("{} {} {}".format(self._id, self._visited_time, self._all_visited_time))


n = int(input())
graph = [0 for i in range(n)]
time = 0

# 頂点登録
for i in range(n):
    u = list(map(int, input().split(' ')))
    adj = []
    if u[1] > 0:
        adj = u[2:u[1]+2]
    graph[u[0]-1] = Vertex(u[0], adj)

# DFS
def dfs(v):
    global time
    time += 1
    v.setVisitedTime(time)
    for child in v.getChildren():
        if not graph[child-1].isVisited():
            dfs(graph[child-1])
    time += 1
    v.setAllVisitedTime(time)

# DFS実行
for v in graph:
    if not v.isVisited():
        dfs(v)

# 回答を出力
for v in graph:
    v.print()

Python: from collections import deque


def conv_list(n):
    adj_matrix = []
    for _ in range(n):
        adj_list = input().split()
        adj_list = list(map(int, adj_list))
        adj_row = [False] * n
        if adj_list[1] > 0:
            for i in adj_list[2:]:
                adj_row[i - 1] = True
        adj_matrix.append(adj_row)
    return adj_matrix


def depth_first_search(adj_matrix, n):
    visited = [None] * n
    count = 1
    searched = [None] * n
    start = 0
    stack = deque()
    stack.append(start)
    visited[start] = 1
    while count <= 2 * n:
        has_edge = adj_matrix[start]
        i = 0
        while i < n:
            if has_edge[i] and visited[i] is None:
                stack.append(i)
                count += 1
                visited[i] = count
                break
            i += 1
        if i < n:
            start = i
        else:
            searched_node = stack.pop()
            count += 1
            searched[searched_node] = count
            if len(stack) > 0:
                start = stack[-1]
            elif count < 2 * n:
                start = visited.index(None)
                stack.append(start)
                count += 1
                visited[start] = count
            else:
                break
    return visited, searched


def main():
    n = int(input())
    adj_matrix = conv_list(n)
    visited, searched = depth_first_search(adj_matrix, n)
    for i in range(n):
        print("{} {} {}".format(i + 1, visited[i], searched[i]))


if __name__ == "__main__":
    main()