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:    #depth first
N=int(input())
V=[]
a=[0]
for i in range(N):
    V.append([int(i) for i in input().split()])
    w=V[i][2:]
    w.sort()
    V[i]=V[i][:2]+w
    a.append(0)
V=sorted(V,key=lambda x:x[0])
c=1
t=1
i=0
r=[1]
a[1]=1
p=[[1,t]]
q=[]
while t<N*2:
    j=2
    while t<N*2 and j-2<V[i][1] and V[i][1]>0 and a[V[i][j]]==1:
        j+=1
    t+=1
    if j-2<V[i][1]:
        a[V[i][j]]=1
        c+=1
        r.append(V[i][j])
        p.append([V[i][j],t])
        i=V[i][j]-1
    else:
        q.append(p[-1]+[t])
        r.pop(-1)
        p.pop(-1)
        if len(r)>0:
            i=r[-1]-1
        else:
            j=1
            while j<N and a[j]==1:
                j+=1
            if j<N:
                t+=1
                i=j-1
                r.append(j)
                p.append([j,t])
q=sorted(q,key=lambda x:x[0])
for i in range(N):
    for j in range(3):
        q[i][j]=str(q[i][j])
    print(" ".join(q[i]))

Python: def DFS(num):
    global time
    time +=1
    color[num]="gray"
    D[num][0]=time
    for i in M[num]:
        if color[i]=="white":
            DFS(i)
    color[num]="black"
    time +=1
    D[num][1]=time


n=int(input())
M=[[] for _ in range(n+1)]
for i in range(n):
    for j in list(map(int,input().split()))[2:]:
        M[i+1].append(j)
color=["white" for _ in range(n+1)]
D=[[0,0] for _ in range(n+1)]
time=0
for i in range(n):
    if color[i+1]=="white":
        DFS(i+1)

for i in range(n):
    print(i+1,*D[i+1])

Python: n=int(input())

next=[[] for i in range(n)]
for i in range(n):
	l=list(map(int,input().split()))
	u=l[0]
	k=l[1]
	for j in range(2,k+2):
		next[u-1].append(l[j]-1)

stk=[]
stk.append(0)
time=1
d=[0 for i in range(n)]
f=[0 for i in range(n)]
know=[0 for i in range(n)]

def dfs(x):
	global time
	know[x]=1
	d[x]=time
	time+=1
	for n in next[x]:
		if know[n]==0:
			dfs(n)
	f[x]=time
	time+=1
	
for i in range(n):
	if know[i]==0:
		dfs(i)

for i in range(n):
	out=[]
	out.append(i+1)
	out.append(d[i])
	out.append(f[i])
	print(*out)

Python: # -*- coding: utf-8 -*-

import sys
sys.setrecursionlimit(10 ** 9)
def input(): return sys.stdin.readline().strip()
def INT(): return int(input())
def MAP(): return map(int, input().split())
def LIST(): return list(map(int, input().split()))
INF=float('inf')

N=INT()
nodes=[[] for i in range(N)]
for i in range(N):
    l=LIST()
    u=l[0]
    l=l[2:]
    for v in l:
        nodes[u-1].append(v-1)
    nodes[u-1].sort()

ans=[[0]*2 for i in range(N)]
visited=[False]*N
time=0
def rec(u):
    if visited[u]:
        return
    visited[u]=True
    global time
    time+=1
    ans[u][0]=time
    for v in nodes[u]:
        rec(v)
    time+=1
    ans[u][1]=time

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