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(u, node_info, matrix):
    # ????????????????????¨??????????????????
    colors = [0] * len(matrix)
    detect_time = [0] * len(matrix)
    finished_time = [0] * len(matrix)
    time = 1
    stack = list()
    stack.append(u)
    colors[u] = 1
    detect_time[u] = time
    while len(stack):
        for i, val in enumerate(matrix[u]):
            if val == 1 and colors[i] == 0:
                time += 1
                stack.append(i)
                colors[i] = 1
                detect_time[i] = time
                u = i
                break
        else:
            time += 1
            e = stack.pop()
            colors[e] = 2
            finished_time[e] = time
            if len(stack):
                u = stack[-1]
    for i in range(len(matrix)):
        print('{} {} {}'.format(i + 1, detect_time[i], finished_time[i]))


if __name__ == '__main__':
    N = int(input())
    matrix = [[0] * N for _ in range(N)]
    color = [0] * N
    for i in matrix:
        node_info = [int(i) for i in input().split()]
        node_i = node_info[0] - 1
        if not node_info[1] == 0:
            for i in node_info[2:]:
                matrix[node_i][i - 1] = 1
    dfs(0, None, matrix)

Python: def dfs(G, u, t, d, visited):
  found = t
  visited.add(u)
  t += 1
  for v in G[u]:
    if v not in visited:
      t = dfs(G, v, t, d, visited)
  complete = t
  d[u] = (found, complete)
  t+=1
  return t


n = int(input())
G = {}
for _ in range(n):
  entries = list(map(int, input().split(' ')))
  u = entries[0]
  k = entries[1]
  G[u] = set()
  for v in entries[2:]:
    G[u].add(v)

d = {}
visited = set()
t = 1
for i in range(1,n+1):
  if i not in visited:
    t = dfs(G, i, t, d, visited)
for i in sorted(d):
  print(i,d[i][0],d[i][1])

Python: n = int(input())
A = [[0 for i in range(n)] for j in range(n)]

for i in range(n):
    u, k, *v = list(map(int, input().split()))
    for j in v:
        A[int(u)-1][int(j)-1] = 1
        # A[int(j)-1][int(u)-1] = 1

for row in A:
    msg = ' '.join(map(str, row))
    # print(msg)

d = [-1] * n
f = [-1] * n

t = 0

# # recursive
# def dfs(u):
#     global t
#     # print('visit:', str(u), str(t))
#     t += 1
#     d[u] = t
#     for i in range(len(A[u])):
#         if A[u][i] == 1 and d[i] == -1:
#             dfs(i)
#     t += 1
#     f[u] = t
            

def get_next(u):
    for i in range(len(A[u])):
        if A[u][i] == 1 and d[i] == -1:
            return i
    return None

def dfs(u):
    global t
    s = []
    s.append(u)
    d[u] = t
    while len(s) > 0:
        p = s[-1]
        v = get_next(p)
        # print(p, 'next:', v)
        # t += 1
        # d[p] = t
        # print('poped:', p)
        
        if v is not None:
            
            if d[v] == -1:
                t += 1
                d[v] = t
                s.append(v)
                # print('[append:', v, 'at', t)
        else:
            t += 1
            # print('complete:', p, 'at', t)
            s.pop()
            f[p] = t


# def dfs(u):
#     s = []
#     t = 0
#     s.append(u)
    
#     while len(s) > 0:
#         p = s.pop()
#         print('init', str(p), d[p], t)
#         if d[p] > -1:
#             print('完了')
#             t += 1
#             f[p] = t
#         else:
#             t += 1
#             d[p] = t
#             print('---visit:', str(p), str(t), 'at', t)
#             has_node = False
#             for i in range(len(A[p])):
#                 if A[p][i] == 1 and d[i] == -1:
#                     print('reserve:', str(i))
#                     has_node = True
#                     s.append(i)
#                     break
#             if not has_node:
#                 t += 1
#                 f[p] = t
#         # print('H_complete:', str(p), str(t))
            


t = 0
for i in range(n):
    if d[i] == -1:
        t += 1
        # print('start from:', str(i))
        dfs(i)


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

Python: def dfs(vertice,connect,went,v_time):
    global time
    for v in connect[vertice]:
        if not went[v]:
            time += 1
            went[v] = time
            dfs(v,connect,went,v_time)
    else:
        time += 1
        v_time[vertice] = time
time = 1
vertices = int(input())
connect = {}
for i in range(vertices):
    temp = input()
    if temp[2] == "0":
        connect[i] = []
    else:
        connect[i] = [int(n) - 1 for n in temp[4:].split(" ")]
went = [0 for n in range(vertices)]
v_time = [0 for n in range(vertices)]
went[0] = time
for i in range(vertices):
    if not v_time[i]:
        dfs(i,connect,went,v_time)
print(went)
print(v_time)

Python: def dfs():
    tt = 0
    for u in range(N):
        if colors[u] == WHITE:
            dfs_visit(u, tt)

def dfs_visit(u, tt):
    tt += 1
    colors[u] = GLAY
    d[u] = tt
    for v in range(N):
        if adjacency_list[u][v] == 1 and colors[v] == WHITE:
            tt = dfs_visit(v, tt)
    tt += 1
    colors[u] = BLACK
    f[u] = tt
    return tt


N = int(input())
adjacency_list = [[0 for j in range(N)] for i in range(N)]
for _ in range(N):
    u, k, *v = map(int, input().split())
    for i in v:
        adjacency_list[u-1][i-1] = 1

WHITE = 0
GLAY = 1
BLACK = 2
colors = [WHITE for _ in range(N)]
d = [0 for _ in range(N)]
f = [0 for _ in range(N)]


dfs()

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

Python: n=int(input())
#V[u]=[k,[v],d,f]
V=[[0,[],0,0]]
for i in range(n):
    v=[int(i) for i in input().split(" ")]
    u=v.pop(0)
    k=v.pop(0)
    v.sort()
    V.append([k,v,0,0])


def is_finished(Id):
    k=V[Id][0]
    v=V[Id][1]
    for i in range(k):
        if V[v[i]][2]==0:
            return v[i]
    return -1

time=1
cur=1
log=[1]
while V[1][3]==0:
    if V[cur][2]==0:
        V[cur][2]=time
        time+=1

    x=is_finished(cur)
    if x!=-1:
        cur=x
        log.append(cur)
    else:
        log.pop(-1)
        V[cur][3]=time
        time+=1

        try:
            cur=log[-1]
        except:
            cur=1


for i in range(1,n+1):
    print(i,V[i][2],V[i][3])