Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

//util
var sc = bufio.NewScanner(os.Stdin)

func nextStr() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func printList(list []int) {
	n := len(list)
	buf := bufio.NewWriter(os.Stdout)
	for _, v := range list[0 : n-1] {
		buf.Write([]byte(fmt.Sprintf("%d ", v)))
	}
	buf.Write([]byte(fmt.Sprintf("%d\n", list[n-1])))
	buf.Flush()
}

func max(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func min(a, b int) int {
	if a > b {
		return b
	} else {
		return a
	}
}

//solve

const MAX = 100
const WHITE = 0
const GRAY = 1
const BLACK = 2

var time, n int

//隣接行列
var M [MAX][MAX]int

//d[i]: 最初にiを訪問した時刻。発見時刻
//f[i]: iの隣接リストを訪問し終えた時刻。完了時刻
var color, d, f [MAX]int

func dfs_visit(u int) {
	color[u] = GRAY
	time++
	d[u] = time
	//隣接を調べる
	for v := 0; v < n; v++ {
		if M[u][v] == 0 {
			continue
		}
		//隣接するvが、未訪問だった場合
		if color[v] == WHITE {
			dfs_visit(v)
		}
	}
	//訪問完了処理
	color[u] = BLACK
	time++
	f[u] = time
	//訪問完了
}

func dfs() {
	//初期化
	for u := 0; u < n; u++ {
		color[u] = WHITE
	}
	time = 0

	//未訪問のuを始点として、深さ優先探索
	for u := 0; u < n; u++ {

		if color[u] == WHITE {
			dfs_visit(u)
		}
	}

	for u := 0; u < n; u++ {
		fmt.Println(u+1, d[u], f[u])
	}
}

func main() {
	sc.Split(bufio.ScanWords)
	n = nextInt()
	for i := 0; i < n; i++ {
		u, k := nextInt(), nextInt()
		M[u-1][u-1] = 0

		//fmt.Println(u, k)
		if k > 0 {
			for j := 0; j < k; j++ {

				v := nextInt()
				M[u-1][v-1] = 1

			}
		}

	}

	dfs()

}

Python: #!/usr/bin/env python3
# -*- coding: utf-8 -*-

import sys

WHITE = 0
GRAY = 1
BLACK = 2


def dbg_record(records):
    for index, record in enumerate(records):
        print("???????????????: %d" % index)
        if isinstance(record, dict):
            print("??\??????: %d" % record.get("visit", -1))
            print("?????????: %d" % record.get("leave", -1))
        else:
            print("?????????")
        print("")


def dfs(matrix):
    def internal_dfs(node_id, current_time):
        if state[node_id] == WHITE:
            # ?¨??????????
            state[node_id] = GRAY
            stack.append(node_id)
            records[node_id] = {"visit": current_time}  # ?¨??????????????¨????

            # ?¬?????¨????????????¨?????§????????????????????¢???
            next_id = None
            for index in range(len(matrix)):
                if matrix[node_id][index] == 1 and state[index] == WHITE:
                    next_id = index
                    break

            if next_id is not None:
                internal_dfs(next_id, current_time + 1)
            elif 0 < len(stack):
                # ?¬?????¨????????????¨?????§?????????????????????????????????????????°?????????
                internal_dfs(stack.pop(), current_time + 1)
        elif state[node_id] == GRAY:
            # ????????????

            # ?¬?????¨????????????¨?????§????????????????????¢???
            next_id = None
            for index in range(len(matrix)):
                if matrix[node_id][index] == 1 and state[index] == WHITE:
                    next_id = index
                    break

            if next_id is not None:
                stack.append(node_id)
                # internal_dfs(next_id, current_time + 1)
                internal_dfs(next_id, current_time)
            elif 0 < len(stack):
                # ?¬?????¨????????????¨?????§?????????????????????????????????????????°?????????
                state[node_id] = BLACK
                records[node_id]["leave"] = current_time  # ????????????????¨????
                internal_dfs(stack.pop(), current_time + 1)
            else:  # ??????????§????????????£???????????¨??? (node_id should be 0)
                state[node_id] = BLACK
                records[node_id]["leave"] = current_time
        elif state[node_id] == BLACK:
            print("Black!!")

    state = [WHITE] * len(matrix)  # White, Gray, Black
    records = [None] * len(matrix)  # Save time when the node is processed
    stack = []

    internal_dfs(0, 1)
    # dbg_record(records)
    return records


if __name__ == "__main__":
    # ??????????????????
    lines = [
        "6",
        "1 2 2 3",
        "2 2 3 4",
        "3 1 5",
        "4 1 6",
        "5 1 6",
        "6 0",
    ]
    # lines = sys.stdin.readlines()

    # Create n * n matrix
    dimension = int(lines[0])
    matrix = []
    for x in range(dimension):
        matrix.append([0] * dimension)

    # Set edge info
    for index, line in enumerate(lines[1:]):
        for edge in [int(x) for x in line.strip().split(" ")[2:]]:
            matrix[index][edge - 1] = 1

    result = dfs(matrix)
    for index, line in enumerate(result):
        print("%d %d %d" % (index + 1, line.get("visit", -1), line.get("leave", -1)))

Python: from sys import stdin
input = stdin.readline

def DFS(node):
    global time
    if discoveredtime[node] == -1:
        discoveredtime[node] = time
        time += 1

        for child in childlist[node]:
            DFS(child)
        
        finishedtime[node] = time
        time += 1

N = int(input())

childlist = [None]*(N+1)
for _ in range(N):
    u, k, *v = map(int, input().split())
    childlist[u] = v

discoveredtime = [-1]*(N+1)
finishedtime = [-1]*(N+1)
time = 1

for i in range(1, N+1):
    if discoveredtime[i] == -1:
        DFS(i)

for i in range(1, N+1):
    print(i, discoveredtime[i], finishedtime[i])

Python: n = int(input())

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

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

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

def dfs(u):
    global time
    time += 1
    flag[u-1] = 1
    d[u-1] = time
    
    for v in adj[u-1]:
        if flag[v-1] == 0:
            dfs(v)

    time += 1
    f[u-1] = time

for i in range(n):
    if flag[i] == 0:
        dfs(i+1)

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

Python: n = int(input())

adj = [None]
for i in range(n):
    adj_i = list(map(int, input().split()[2:]))
    adj.append(adj_i)

# searched or not, number of vertex, discovery time and finishing time.
sndf = [None]
for i in range(1, n + 1):
    sndf.append([False, i])

path = []

time = 0

def dfs(u):
    global time
    sndf[u][0] = True
    time += 1
    sndf[u].append(time)

    for v in adj[u]:
        if not sndf[v][0]:
            dfs(v)
    time += 1
    sndf[u].append(time)


for i in range(1, n + 1):
    if not sndf[i][0]:
        dfs(i)

for x in sndf[1:]:
    print(*x[1:])