Go: package main

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

var N int
var A [][]int
var t int
var color, d, f []int

const (
	WHITE = iota
	GRAY
	BLACK
)

func dfsVisit(u int) {
	color[u] = GRAY
	t ++
	d[u] = t
	for v:=0; v<N; v++ {
		if A[u][v] == 0 {
			continue
		}
		if color[v] == WHITE {
			dfsVisit(v)
		}
	}
	color[u] = BLACK
	t++
	f[u] = t
}

func dfs() {
	for u:=0; u<N; u++ {
		if color[u] == WHITE {
			dfsVisit(u)
		}
	}
	for u:=0; u<N; u++{
		fmt.Printf("%d %d %d\n", u+1, d[u], f[u])
	}
}


func nextInt(scanner *bufio.Scanner) int {
	scanner.Scan()
	num, _ := strconv.Atoi(scanner.Text())
	return num
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	N = nextInt(scanner)
	color = make([]int, N)
	d = make([]int, N)
	f = make([]int, N)
	A = make([][]int, N)
	for i:=0; i<N; i++{
		A[i] = make([]int, N)
	}
	for i:=0; i<N; i++{
		index := nextInt(scanner) - 1
		cnt := nextInt(scanner)
		for j:=0; j<cnt; j++ {
			v := nextInt(scanner) - 1
			A[index][v] = 1
		}
	}
	dfs()
}

Python: def solve(v, g, ans, time):
    if ans[v]["found"] != 10**9:
        return time
    time += 1
    # print(v + 1, time, file=sys.stderr)
    ans[v]["found"] = time
    for a in g[v]:
        time = solve(a, g, ans, time)
    time += 1
    # print(v + 1, time, file=sys.stderr)
    ans[v]["complete"] = time
    return time


def resolve():
    n = int(input())
    V = [list(map(int, input().split())) for _ in range(n)]
    g = [[] for _ in range(n)]
    for v, k, *a in V:
        v -= 1
        for ai in a:
            ai -= 1
            g[v].append(ai)
    ans = [{"found": 10**9, "complete": -1} for _ in range(n)]
    time = solve(0, g, ans, 0)
    for i in range(n):
        if ans[i]["found"] == 10**9:
            solve(i, g, ans, time)
        print(i + 1, ans[i]["found"], ans[i]["complete"])


resolve()

Python: def dfs_visit(u):
    global dfs_color, d, f, t
    color[u] = GRAY
    d[u] += t
    t += 1
    for v in range(n):
        if M[u][v] == 0:
            continue
        if color[v] == WHITE:
            dfs_visit(v)
    color[u] = BLACK
    f[u] += t
    t += 1

n = int(input())
M = [[False for i in range(n)] for j in range(n)]
WHITE = 0
GRAY = 1
BLACK = 2
color = [WHITE for i in range(n)]
d = [0 for i in range(n)]
f = [0 for i in range(n)]
t = 1
for i in range(n):
        a = list(map(int, input().split()))
        for j in range(a[1]):
            M[a[0] - 1][a[j + 2] - 1] = True
for u in range(n):
    if color[u] == WHITE:
        dfs_visit(u)
for u in range(n):
    print(str(u + 1), str(d[u]), str(f[u]), sep = " ")

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

import sys

UNVISITED, VISITED_IN_STACK, POPPED_OUT = 0, 1, 2


def generate_adj(v_info):
    for v_detail in v_info:
        v_adj_list = v_detail[2:]
        assert len(v_adj_list) == int(v_detail[1])
        for each in v_adj_list:
            init_adj_matrix[int(v_detail[0]) - 1][int(each) - 1] = 1
    return init_adj_matrix


def graph_dfs(v_init):
    global time
    # init the first node of overall graph iterations(times >= 1)
    vertex_visit_stack.append(v_init)
    vertex_status_list[v_init] = VISITED_IN_STACK
    vertex_d_time[v_init] += time
    # init end
    while len(vertex_visit_stack) > 1:
        current_vertex = vertex_visit_stack[-1]
        next_vertex = get_adj_vertices(_vertex=current_vertex)
        # print('start', current_vertex, next_vertex, vertex_status_list, vertex_visit_stack)

        if next_vertex:
            if vertex_status_list[next_vertex] is UNVISITED:
                vertex_status_list[next_vertex] = VISITED_IN_STACK
                time += 1
                vertex_d_time[next_vertex] += time
                vertex_visit_stack.append(next_vertex)
                # print('on', current_vertex, next_vertex, vertex_status_list, vertex_visit_stack)
        else:
            # print('no out degree', current_vertex)
            vertex_visit_stack.pop()
            vertex_status_list[current_vertex] = POPPED_OUT
            time += 1
            vertex_f_time[current_vertex] += time
        # print('end', current_vertex, vertex_status_list, vertex_visit_stack)

    return None


def get_adj_vertices(_vertex):
    for j in range(vertex_num):
        if adj_matrix[int(_vertex) - 1][j]:
            adj_matrix[int(_vertex) - 1][j] = 0
            return j + 1
    return None


def dfs_start():
    global time
    for i in range(vertex_num):
        if vertex_status_list[i + 1] == UNVISITED:
            # print('round', i + 1)
            graph_dfs(v_init=i + 1)
            time += 1


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    vertex_num = int(_input[0])
    vertex_info = list(map(lambda x: x.split(), _input[1:]))
    init_adj_matrix = [[0] * vertex_num for _ in range(vertex_num)]
    # assert len(vertex_info) == vertex_num
    # config length -> (vertex_num + 1)
    vertex_visit_stack = [-1]
    vertex_status_list = [UNVISITED] * vertex_num
    vertex_status_list.insert(0, -1)
    vertex_d_time, vertex_f_time = ([0] * (vertex_num + 1) for _ in range(2))

    adj_matrix = generate_adj(vertex_info)

    time = 1
    dfs_start()

    for k in range(vertex_num):
        print(k + 1, vertex_d_time[k + 1], vertex_f_time[k + 1])

Python: n = int(input())
G = []
for i in range(n):
    T = [0]*n
    G.append(T)
for i in range(n):
    L = list(map(int,input().split()))
    for j in range(2,len(L)):
        G[i][L[j]-1] += 1
time = 1
D = [-1]*n
F = [-1]*n
def dfs(src):
    global time
    D[src] = time
    time += 1
    for dst in range(n):
        if G[src][dst] == 1 and D[dst] == -1:
            dfs(dst)
    F[src] = time
    time += 1
for root in range(n):
    if D[root] == -1:
        dfs(root)
for i in range(n):
    print(i+1,D[i],F[i])