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
		}
	}

	// TODO: always start with 1?
	timer := 1
	visit(1, &timer, childrenMap, timeRecordMap)
	for k, v := range timeRecordMap {
		fmt.Printf("%d %d %d\n", k+1, v.discoverTime, v.finishTime)
	}
}

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

"""
input:
6
1 2 2 3
2 2 3 4
3 1 5
4 1 6
5 1 6
6 0

output:
1 1 12
2 2 11
3 3 8
4 9 10
5 4 7
6 5 6
"""
import sys

UNVISITED, VISITED_IN_STACK, POPPED_OUT = 0, 1, 2


def generate_adj_matrix(v_info):
    for v_detail in v_info:
        v_index, adj_num, *adj_list = map(int, v_detail)
        # assert len(adj_list) == adj_num
        init_adj_table[v_index].extend(sorted(adj_list, reverse=True))
    return init_adj_table


def graph_dfs(v_init):
    global time

    # init the first node of overall graph iterations(times >= 1)
    stack.append(v_init)
    d_time[v_init] += time
    # init end

    while stack:
        current = stack[-1]
        v_table = adj_table[current]
        color[current]=VISITED_IN_STACK
        # if adj is None, current's adj(s) have been all visited
        adj = v_table.pop() if v_table else None

        if adj:
            if color[adj] is UNVISITED:
                color[adj] = VISITED_IN_STACK
                time += 1
                d_time[adj] += time
                stack.append(adj)
        else:
            stack.pop()
            color[current] = POPPED_OUT
            time += 1
            f_time[current] += time

    return None


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


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    vertices = int(_input[0])
    v_info = map(lambda x: x.split(), _input[1:])
    init_adj_table = tuple([] for _ in range(vertices + 1))
    # assert len(vertex_info) == vertex_num

    # config length = (vertex_num + 1)
    stack = []
    color = [UNVISITED] * (vertices + 1)
    d_time, f_time = ([0] * (vertices + 1) for _ in range(2))

    adj_table = generate_adj_matrix(v_info)
    # timing start from 1
    time = 1
    dfs_start()

    for index, v in enumerate(zip(d_time[1:], f_time[1:]), 1):
        print(index, *v)

Python: n=int(input())
D=[0]*(n+1)
F=[0]*(n+1)
v=[[] for i in range(n+1)]
flg=True
t=1
for i in range(n):
  a=list(map(int,input().split()))
  v[a[0]]=sorted(a[2:])

def dfs(p):
  global t
  if D[p]!=0: return
  D[p]=t
  t+=1
  for i in v[p]:
    if D[i]==0: dfs(i)
  F[p]=t
  t+=1

while flg:
  flg=False
  for i in range(1,n+1):
    if D[i]==0:
      flg=True
      dfs(i)

for i in range(1,n+1):
  print(f'{i} {D[i]} {F[i]}')

Python: from collections import deque
n = int(input())
v = {i:[] for i in range(n)}
for i in range(n):
    u = list(map(int, input().split()))
    for j in range(2, 2+u[1]):
        v[u[0]-1].append(u[j]-1)

global cnt1 
cnt1 = 0
visited = [False for _ in range(n)]
f = [0 for _ in range(n)]
l = [0 for _ in range(n)]
def DFS(now, visited):
    global cnt1
    cnt1 += 1
    f[now] = cnt1
    visited[now] = True
    for nv in v[now]:
        if visited[nv]:
            continue
        DFS(nv, visited)
    cnt1 += 1
    l[now] = cnt1

for value in range(n):
    if not visited[value]:
        DFS(value, visited)
    
for i in range(n):
    print(i+1, f[i], l[i])

Python: 
n=int(input())

l=[[0 for i in range(n)] for j in range(n)]##静的確保 隣接行列
d=[0 for i in range(n)]##発見
f=[0 for i in range(n)]##完了
stack=[]##スタック
check=[]

for i in range(n):
    p=[int(x) for x in input().split()]
    
    for j in range(n):
        if j+1 in p[2:]:
            l[i][j]=1
##print("---隣接行列---")
##print(l)

time=1


while len(check)<n:
    for i in range(n):
        if i+1 not in check:
            stack+=[i+1]
            d[i]=time
            break
        else: pass

    while len(stack)!=0:
        ##print("----------while---------")
        for i in range(n):
            if l[stack[-1]-1][i]==1 and not i+1 in check and stack[-1]-1!=i:
                time+=1
                d[i]=time
                stack+=[i+1]

               ## print("stack:",stack)
               ## print("check:",check)
               ## print("d[",i,"]:",d[i])
                break
            elif i==n-1:
##最深    
                check+=[stack[-1]]
                time+=1
                f[stack.pop()-1]=time

               ## print("f[",i,"]:",f[i])
               ## print("check:",check)
    time+=1


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

Python: n = int(input())
B = [[0 for i in range(n)] for j in range(n)]
chk = [0 for i in range(n)]
s = []
i_array = [0 for i in range(n)]
time = 1
node_start_time = [0 for i in range(n)]
node_finish_time = [0 for i in range(n)]

for i in range(n):
    A = list(map(int,input().split()))
    for j in range(A[1]):
        B[A[0]-1][A[j+2]-1] = 1

for i in range(n):
    if(chk[i] == 1):
        continue
    chk[i] = 1
    node_start_time[i] = time
    time += 1
    s.append(i)
    while(len(s) != 0):
        flag = 0
        v = s[len(s)-1]
        for j in range(i_array[v],n):
            if(B[v][j] == 1 and chk[j] == 0):
                chk[j] = 1
                s.append(j)
                node_start_time[j] = time
                time += 1
                i_array[v] = j+1
                flag = 1
                break
        if(flag == 0):
            s.pop()
            node_finish_time[v] = time
            time += 1

for i in range(n):
    print(i+1,node_start_time[i],node_finish_time[i])

Python: def main():
    n = int(input())
    _next, state, d, f = [], [False] * n, [0] * n, [0] * n
    for _ in range(n):
        u, k, *v = map(lambda s: int(s) - 1, input().split())
        _next.append(sorted(v, reverse=True))
    stack = []
    time = 0

    while True:
        for i in range(n):
            if not state[i]:
                stack.append(i)
                state[i] = True
                time += 1
                d[i] = time
                break
        if not stack:
            break
        while stack:
            u = stack[-1]
            if _next[u]:
                v = _next[u].pop()
                if not state[v]:
                    state[v] = True
                    time += 1
                    d[v] = time
                    stack.append(v)
            else:
                time += 1
                f[u] = time
                stack.pop()

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


if __name__ == '__main__':
    main()