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: n = int(input())
M = [[0]*n for _ in range(n)]

for _ in range(n):
    u, k, *V = map(int, input().split())
    if k == 0:
        continue
    else:
        for v in V:
            M[u-1][v-1] = 1

color = ['White']*n

time = 0
d = [0]*n
f = [0]*n
def dfs_visit(u=0):
    global time
    color[u] = 'Gray'
    time += 1
    d[u] = time
    for v in range(n):
        if M[u][v] == 0:
            continue
        if color[v] == 'White':
            dfs_visit(v)
    color[u] = "Black"
    time += 1
    f[u] = time

def dfs():
    for u in range(n):
        if color[u] == 'White':
            dfs_visit(u)
    for u in range(n):
        print('{} {} {}'.format(u+1, d[u], f[u]))


dfs()

Python: # coding: utf-8
# Your code here!

import sys
read = sys.stdin.read
readline = sys.stdin.readline


def dfs(G, v, d, f, time):
    time += 1
    d[v] = time

    for e in G[v]:
        if d[e] == 0:
            time = dfs(G, e, d, f, time)

    time += 1
    f[v] = time

    return time


def main():
    n = int(readline())

    E = [[]]
    for _ in range(n):
        u,k,*v = map(int, readline().split())
        E.append(v)

    d = [0] * (n+1)
    f = [0] * (n+1)
    time = 0
    
    for i in range(1,n+1):
        if d[i] == 0:
            time = dfs(E, i, d, f, time)
    
    for i in range(1, n+1):
        print(i, d[i], f[i])


if __name__ == "__main__":
    main()

Python: #!/usr/bin/env python3
from enum import Enum


class DFS():
    class Color(Enum):
        WHITE = 0
        GRAY = 1
        BLACK = 2

    def __init__(self, M, n):
        self.M = M
        self.n = n
        self.color = [self.Color.WHITE for _ in range(self.n)]
        self.d, self.f = [-1] * self.n, [-1] * self.n
        self.tt = 0
        self.nt = [0] * self.n

    def next(self, u: int):
        while self.nt[u] < self.n:
            v = self.nt[u]
            self.nt[u] = v + 1
            if self.M[u][v] != 0:
                return v
        return -1

    def dfs_visit(self, r: int):
        S = []                  # list をスタックとして使う
        S.append(r)
        self.color[r] = self.Color.GRAY
        self.tt += 1
        self.d[r] = self.tt
        while len(S) > 0:
            # スタックの一番上（= listの末尾）の値を取得 ※ pop()するとlistからなくなるので[-1]でアクセス
            u = S[-1]
            v = self.next(u)
            if v != -1:
                if self.color[v] == self.Color.WHITE:
                    self.color[v] = self.Color.GRAY
                    self.tt += 1
                    self.d[v] = self.tt
                    S.append(v)
            else:
                S.pop()
                self.color[u] = self.Color.BLACK
                self.tt += 1
                self.f[u] = self.tt

    def dfs(self):
        for u in range(self.n):
            if self.color[u] == self.Color.WHITE:
                self.dfs_visit(u)

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


def main():
    n = int(input())
    M = [[0] * n for _ in range(n)]

    for i in range(n):
        line = input()
        inputs = [int(x) for x in line.split(' ')]
        u = inputs.pop(0)
        u -= 1                  # 0 オリジンへ変換
        _ = inputs.pop(0)       # k （使わない...）
        for v in inputs:
            v -= 1              # 0 オリジンへ変換
            M[u][v] = 1

    DFS(M, n).dfs()


if __name__ == '__main__':
    main()

Python: n = int(input())
V = [[] for _ in range(n)]
for i in range(n):
    data = list(map(int, input().split(" ")))
    V[i] = data[2:]

answer = [[None, None] for _ in range(n)]

counter = 1


def dfs(v):
    global counter
    if answer[v][0] == None:
        answer[v][0] = counter
        counter += 1
        # ノードの子供の管理
        for e in V[v]:
            dfs(e-1)
        answer[v][1] = counter
        counter += 1


for i in range(len(answer)):
    if answer[i][0] == None:
        dfs(i)

for i in range(len(answer)):
    print(str(i+1) + " " + " ".join(map(str, answer[i])))

Python: def depth_search(i, adj, d, f, t):
    if d[i-1]:
        return t
    d[i-1] = t
    t += 1                                          
    for v in adj[i-1]:
        t = depth_search(v, adj, d, f, t)
    f[i-1] = t                                      
    t += 1
    return t

n = int(input())
adj = [list(map(int, input().split()))[2:] for _ in range(n)] 

d = [0] * n
f = [0] * n

t = 1
for i in range(n):
    if d[i] == 0:
        t = depth_search(i+1, adj, d, f, t)

for i, df in enumerate(zip(d, f)):
    print(i + 1, *df)

Python: def MAIN():
    n = int(input())
    ans = [[i, 0, 0] for i in range((n + 1))]
    G = [[] for _ in range((n + 1))]
    for _ in range(n):
        u, k, *v = map(int, input().split())
        G[u] = v
    cnt = 1
    def dfs(u):
        nonlocal ans
        if ans[u][1] != 0:
            return
        nonlocal cnt
        ans[u][1] = cnt
        cnt += 1
        for v in G[u]:
            dfs(v)
        ans[u][2] = cnt
        cnt += 1
    for i in range(1, n + 1):
        if ans[i][1] == 0:
            dfs(i)
    for i in range(1, n + 1):
        print(*ans[i])
MAIN()