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
		}
	}

	timer := 1
	for {
		startNode := findStartNode(childrenMap, timeRecordMap)
		if startNode > 0 {
			visit(startNode, &timer, childrenMap, timeRecordMap)
		} else {
			break
		}
	}
	for k, v := range timeRecordMap {
		fmt.Printf("%d %d %d\n", k+1, v.discoverTime, v.finishTime)
	}
}

func findStartNode(childrenMap [][]int, timeRecordMap []TimeRecord) int {
	x := -1
	for node, timeRecord := range timeRecordMap {
		if timeRecord.discoverTime < 0 {
			x = node + 1
			break
		}
	}
	if x < 0 {
		return -1
	}

	found := false
	i := 0
	for i < len(childrenMap) {
		children := childrenMap[i]
		for j := 0; j < len(children); j++ {
			if children[j] == x {
				x = j + 1
				found = true
				break
			}
		}
		if found {
			i = 0
		} else {
			i++
		}
	}
	return x
}

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

d_num = int(stdin.readline().strip())

graph = [[] for _ in range(d_num+1)]
for _ in range(d_num):
    u, k, *neighbors = map(int, stdin.readline().split())
    for v in neighbors:
        graph[u].append(v)

visited = set()
timestamps = [None for _ in range(d_num+1)]

def dfs(u, stmp):
    visited.add(u)
    entry = stmp

    stmp += 1
    for v in graph[u]:
        if v not in visited:
            stmp = dfs(v, stmp)

    timestamps[u] = entry, stmp
    return stmp+1

dfs(1, 1)

for num, (entry, leave) in enumerate(timestamps[1:], 1):
    print(num, entry, leave)

Python: N = int(input())
UK = [list(map(int,input().split())) for _ in range(N)]

class Graph:
    def __init__(self,vertex,edge):
        self.v = vertex
        self.e = edge
        self.v_color = [False for _ in range(N)]

    def color(self,u):
        self.v_color[u-1] = True

    def v_exists(self,u):
        flag = False
        for v in self.v:
            if (u,v) in self.e and self.v_color[v-1] == False:
                flag = True
                break
        return flag

V = [i+1 for i in range(N)]
E = []
for i in range(N):
    for j in range(len(UK[i])-2):
        E.append((i+1,UK[i][j+2]))

g = Graph(V,E)

ts = [[0 for _ in range(2)] for _ in range(N+1)]
time = 0

def dfs(u):
    global time
    time += 1
    g.color(u)
    if ts[u-1][0] == 0:
        ts[u-1][0] = time
    while g.v_exists(u):
        for v in g.v:
            if (u,v) in g.e and g.v_color[v-1] == False:
                dfs(v)
    time += 1
    if ts[u-1][1] == 0:
        ts[u-1][1] = time

for i in range(N):
    if g.v_color[i] == False:
        dfs(i+1)

for i in range(N):
    print(i+1,ts[i][0],ts[i][1])

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


if __name__ == '__main__':

    n = int(input())
    M = [[0 for i in range(n)] for j in range(n)]
    for _ in range(n):
        l = list(map(int, input().split(" ")))
        u = l[0]
        k = l[1]
        if k != 0:
            for v in l[2:]:
                M[u-1][v-1] = 1
    
    color = [0]*n
    d = [0]*n
    f = [0]*n
    time = 0
    
    def dfs(u): #depth-first search
        global time
        color[u] = 1
        time += 1
        d[u] = time
        for v in range(n):
            if M[u][v] == 1 and color[v] == 0:
                dfs(v)
        color[u] = 2
        time += 1
        f[u] = time
    
    for u in range(n):
        if color[u] == 0:
            dfs(u)

    for u in range(n):
        print(u+1, d[u], f[u])

Python: from collections import deque
n = int(input())
u = []
k = []
v = []

for i in range(n):
    tmp = list(map(int, input().split()))
    u.append(tmp[0])
    k.append(tmp[1])
    if tmp[1] != 0:
        v.append(tmp[2:])
    else:
        v.append([])
        
check = [0]*n
intime = [0]*n
outtime = [0]*n
time = 1

def dfs(v, start):
    d = deque()
    d.append(start)
    global check
    global intime
    global outtime
    global time
    check[start-1] = 1
    intime[start-1] = time
    time += 1
    while len(d) > 0:
        visit = d[-1]
        tf = True
        for dtn in v[visit-1]:
            if check[dtn-1] == 0:
                d.append(dtn)
                check[dtn-1] = 1
                intime[dtn-1] = time
                time += 1
                tf = False
                break
        if tf:
            outtime[visit-1] = time
            d.pop()
            time += 1

dfs(v, 1)
for i in range(n):
    if check[i] == 0:
        dfs(v, i+1)
for i in range(n):
    print(i+1, intime[i], outtime[i])

Python: #import pysnooper
#import os,re,sys,operator,math,heapq,string
#from collections import Counter,deque
#from operator import itemgetter
#from itertools import accumulate,combinations,groupby,combinations_with_replacement
from sys import stdin,setrecursionlimit
#from copy import deepcopy
setrecursionlimit(10**6)

#@pysnooper.snoop()
def dfs(v,s):
    seen[v]=True
    first[v]=s
    s+=1
    #print(v,g[v])
    for i in g[v]:
        if seen[i]:
            continue
        s=dfs(i,s)
    #print(s)
    last[v]=s
    return s+1

n=int(stdin.readline().rstrip())
seen=[False]*n
first=[0]*n
last=[0]*n
g=[[] for _ in range(n)]
s=1
for i in range(n):
    v=list(map(int,stdin.readline().rstrip().split()))
    for j in v[2:]:
        g[v[0]-1].append(j-1)
for i in range(n):
    if not seen[i]:
        s=dfs(i,s)
for i in range(n):
    print(i+1,first[i],last[i])

Python: n = int(input())

m = [[0 for i in range(n)] for j in range(n)]

for i in range(n):
    com = list(map(int, input().split()))
    for j in range(com[1]):
        m[i][com[j+2]-1] = 1

color = ["white" for i in range(n)]

d = [0 for i in range(n)]
f = [0 for i in range(n)]
time = 0

def dfs(u):
    global time
    time += 1
    color[u] = "gray"
    d[u] = time
    for i in range(n):
        if m[u][i] and color[i] == "white":
            dfs(i)
    color[u] = "black"
    time += 1
    f[u] = time

dfs(0)
for i in range(n):
    print(i+1, d[i], f[i])

Python: n = int(input())
mat = [[0] * n for _ in range(n)]
d, f = [0] * n, [0] * n
for _ in range(n):
    adj = list(map(int, input().split()))
    i = adj[0]
    v = adj[2:]
    for j in v:
        mat[i - 1][j - 1] = 1

time, current = 0, 0
stack = []
while 0 in f:
    if not stack:
        for i, v in enumerate(f):
            if v == 0:
                stack.append(i)
                time += 1
                d[i] = time
                break
    time += 1
    current = stack[-1]
    for i in range(len(mat[current])):
        if mat[current][i] and not d[i]:
            current = i
            d[i] = time
            stack.append(i)
            break
    else:
        f[current] = time
        current = stack.pop()

for l in zip(range(1, n + 1), d, f):
    print(*l)