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: def dfs(vum,v,d,f,t):
    # print('first')
    # print(vum,v,d,f,t)
    if f[v] >= 0:
        return d,f,t
    t += 1
    d[v] = t
    for u in vum[v]:
        # print(v, d[v], f[v], u, d[u], f[u])
        if d[u] >= 0:
            # print('skip', str(v), str(u))
            continue
        d,f,t = dfs(vum,u,d,f,t)
    t += 1
    f[v] = t
    # print(v, d[v], f[v])
    # print('last')
    # print(vum,v,d,f,t)
    return d,f,t

def main():
    n = int(input())
    rows = []
    for i in range(n):
        rows.append([int(x) for x in input().split()])

    vum = {}
    for v,row in enumerate(rows):
        u,k = row[0],row[1]
        ul = []
        if k > 0:
            for j in row[2:]:
                ul.append(j-1)
        vum.update({v:ul})

    # print(vum)
    d = [-1]*len(vum)
    f = [-1]*len(vum)
    t = 0
    for v in vum:
        d,f,t = dfs(vum,v,d,f,t)
    for i,(j,k) in enumerate(zip(d,f)):
        print(i+1,j,k)

if __name__ == '__main__':
    main()

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

Python: n=int(input())
d=[0 for _ in range(n+1)]
f=[0 for _ in range(n+1)]
G=[]
G.append([])
for i in range(n):
    u,k,*v=map(int,input().split())
    G.append(v)

checked=[False for _ in range(n+1)]
timestamp=1

def dfs(id):
    global timestamp
    d[id]=timestamp
    checked[id]=True
    timestamp+=1
    for v in G[id]:
        if not checked[v]:
            dfs(v)
    f[id]=timestamp
    timestamp+=1

for id in range(1,n+1):
    if not checked[id]:
        dfs(id)

for i in range(1,n+1):
    print("{0} {1} {2}".format(i,d[i],f[i]))

Python: def visit(u):
    global visit_color, d, f, t
    color[u] = GRAY
    d[u] += t
    t += 1
    for v in range(n):
        if (M[u][v] == 0):
            continue
        else:
            if (color[v] == WHITE):
                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)]
for i in range(n):
    tmp = list(map(int, input().split()))
    for j in range(tmp[1]):
        M[tmp[0]-1][tmp[j+2]-1] = True

WHITE = 0
GRAY = 1
BLACK = 2
color = [WHITE for i in range(n)]
d, f = [0 for i in range(n)]
t = 1

for u in range(n):
    if (color[u] == WHITE):
        visit(u)
for u in range(n):
    print(str(u+1), str(d[u]), str(f[u]), sep = " ")

Python: n = int(input())
G = []
checked = [False for i in range(n + 1)]
d = [0 for i in range(n + 1)]
f = [0 for i in range(n + 1)]
G.append([])
for i in range(n):
    u, k, *v = map(int, input().split())
    G.append(v)

timestamp = 1

def dfs(id):
    global timestamp

    checked[id] = True
    d[id] = timestamp
    timestamp += 1
    for v in G[id]:
        if not checked[v]:
            dfs(v)
    f[id] = timestamp
    timestamp += 1

dfs(1)

for i in range(1, n + 1):
    print("{0} {1} {2}".format(i, d[i], f[i]))

Python: # coding: utf-8
import itertools
import math
import bisect

class Node:
    def __init__(self, id, next, rest):
        self.id = id
        self.before = None
        self.next = next
        self.rest = rest
        self.d = None
        self.f = None

    def update_next(self):
        self.next = first(self.rest)
        self.rest = rest(self.rest)


N = int(input())
graph = []
for _ in range(N):
    l = list(map(int, input().split(" ")))
    id = l[0]
    if l[1] != 0:
        next = l[2]
    else:
        next = None
    if l[1] >= 2:
        rest = l[3:]
    else:
        rest = []
    graph.append(Node(l[0], next, rest))

def first(l):
    if l==None:
        return None
    if len(l) == 0:
        return None
    else:
        return l[0]

def rest(l):
    if l == None:
        return None
    if len(l) >= 2:
        return l[1:]
    else:
        return None

def dfs(graph):
    stack = [graph[0]]
    stack[-1].d = 1
    tansakuzumi = [1]
    mitansaku = list(range(1, len(graph)+1))
    res_graph = []
    t = 2
    while len(stack) != 0:
        tansakuzumi.append(stack[-1].id)
        if stack[-1].id in mitansaku:
            mitansaku.remove(stack[-1].id)
        if stack[-1].next == None:
            stack[-1].f = t
            res_graph.append(stack.pop())
            t += 1
        elif stack[-1].next in tansakuzumi:
            stack[-1].update_next()
        else:
            stack.append(graph[stack[-1].next-1])
            stack[-2].update_next()
            stack[-1].d = t
            t += 1
        if len(stack) == 0 and len(mitansaku) >= 1:
            stack.append(graph[mitansaku[0]-1])
            stack[-1].d = t
            t += 1
    return res_graph




res_graph = dfs(graph)

res_graph.sort(key=lambda x: x.id)

for n in res_graph:
    print("{} {} {}".format(n.id, n.d, n.f))

Python: def dfs(v, cnt):
    D[v] = cnt
    cnt += 1
    for c in edge[v]:
        if D[c] == -1:
            cnt = dfs(c, cnt)
    F[v] = cnt
    cnt += 1
    return cnt


V = int(input())
edge = [[] for _ in range(V)]
for _ in range(V):
    u, _, *v = map(lambda x: int(x)-1, input().split())
    edge[u] = sorted(v)
D, F = [-1] * V, [-1] * V
_ = dfs(0, 1)
for i, (d, f) in enumerate(zip(D, F)):
    print(i, d, f)

Python: n = int(input())
a = [[0]*n for i in range(n)]
  
for i in range(n):
    v = list(map(int, input().split()))
    u = v[0]
    k = v[1]
    for j in range(k):
        a[u - 1][v[2 + j] - 1] = 1

d = [0] * n
f = [0] * n
isDiscovered = [False] * n
time_stamp = 0

def dfs(x):
    global time_stamp
    isDiscovered [x] = True
    time_stamp = time_stamp + 1
    d[x] = time_stamp
    for i in range(n):
        if a[x][i] == 1 and isDiscovered[i] == False:
            dfs(i)
    time_stamp = time_stamp + 1
    f[x] = time_stamp

for i in range(n):
    if isDiscovered[i] == False:
        dfs(i)

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