Go: #include <bits/stdc++.h>
using namespace std;
static const int WHITE = 0;
static const int GRAY  = 1;
static const int BLACK = 2;
static const int N     = 100;

int n, tt;
vector<vector<int>> M(N, vector<int>(N));
vector<int> color(N), d(N), f(N);

void dfs_visit(int u) {
  color[u] = GRAY;
  d[u]     = ++tt;
  for (int v = 0; v < n; v++) {
    if (M[u][v] == 0) continue;
    if (color[v] == WHITE) { dfs_visit(v); }
  }
  color[u] = BLACK;
  f[u]     = ++tt;
}

void dfs() {
  tt = 0;

  for (int u = 0; u < n; u++) {
    if (color[u] == WHITE) dfs_visit(u);
  }
  for (int u = 0; u < n; u++) {
    printf("%d %d %d\n", u + 1, d[u], f[u]);
  }
}

int main() {
  int u, v, k;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> u >> k;
    u--;
    for (int j = 0; j < k; j++) {
      cin >> v;
      v--;
      M[u][v] = 1;
    }
  }

  dfs();
}

Python: import math
import copy
import sys
import fractions
# import numpy as np
# import statistics
import decimal
import heapq
import collections
import itertools
import bisect


# from operator import mul

# sys.setrecursionlimit(100001)


# input = sys.stdin.readline
# sys.setrecursionlimit(10**6)

# ===FUNCTION===

def getInputIntList():
    outputDataList = []
    inputData = input().split()
    outputDataList = [int(n) for n in inputData]

    return outputDataList


def getSomeInputInt(n):
    outputDataList = []
    for i in range(n):
        inputData = int(input())
        outputDataList.append(inputData)

    return outputDataList


def getSomeInputListInt(n):
    inputDataList = []
    outputDataList = []
    for i in range(n):
        inputData = input().split()
        inputDataList = [int(n) - 1 for n in inputData]
        outputDataList.append(inputDataList)

    return outputDataList


# ===CODE===

n = int(input())

data = getSomeInputListInt(n)

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

edge = []
for d in data:
    edge.append(d[2:])


def dfs(i, cnt):
    if len(ans[i]) > 0:
        return cnt

    cnt += 1

    ans[i].append(cnt)
    for j in range(len(edge[i])):
        cnt = dfs(edge[i][j], cnt)

    cnt += 1
    ans[i].append(cnt)

    return cnt

tmp = 0
for i in range(n):
    tmp = dfs(i, tmp)

for i in range(n):
    print(i + 1, *ans[i], sep=" ")

Python: class Node:
    def __init__(self, data):
        self.data = data
        self.neighbors = list()
        self.find_time = 0
        self.end_time = 0

N = int(input())
work_id = 0
nodes = list()
nodes.append(Node(0))


for _ in range(N):
    tmp_list = list( map(int, input().split()) )
    node = Node(tmp_list[0])
    for i in range(tmp_list[1]):
        node.neighbors.append(tmp_list[i+2])
    nodes.append(node)
    nodes[0].neighbors.append(node.data)

# for node in nodes:
#     print(node.data, ":", node.neighbors)


def search(node):
    global work_id

    if node.find_time != 0:
        return
    
    if node.data != 0:
        work_id += 1
        node.find_time = work_id

    if len(node.neighbors) > 0:
        for neighbor in node.neighbors:
            search(nodes[neighbor])
    
    if node.data != 0:
        work_id += 1
        node.end_time = work_id

search(nodes[0])

for node in nodes:
    if node.data == 0: continue
    print(node.data, node.find_time, node.end_time)

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 dfs(v_init):
    global timer

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

    while stack:
        current = stack[-1]
        v_table = adj_table[current]
        visited[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 visited[adj] is UNVISITED:
                visited[adj] = VISITED_IN_STACK
                timer += 1
                d_time[adj] += timer
                stack.append(adj)
        else:
            stack.pop()
            visited[current] = POPPED_OUT
            timer += 1
            f_time[current] += timer

    return None


def dfs_init():
    global timer
    for v in range(v_num):
        if visited[v + 1] == UNVISITED:
            timer += 1
            dfs(v + 1)


if __name__ == '__main__':
    _input = sys.stdin.readlines()
    v_num = int(_input[0])
    vertices = map(lambda x: x.split(), _input[1:])

    # config length = (v_num + 1)
    # stack = []
    visited = [UNVISITED] * (v_num + 1)
    d_time, f_time = ([0] * (v_num + 1) for _ in range(2))
    adj_table = tuple([] for _ in range(v_num + 1))
    for v_info in vertices:
        v_index, adj_num, *adj_list = map(int, v_info)
        # assert len(adj_list) == adj_num
        adj_table[v_index].extend(sorted(adj_list, reverse=True))

    # timing start from 1
    timer = 0
    dfs_init()

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

Python: WHITE = 0
GRAY = 1
BLACK = 2
tt = -1

def next(u, m, n, nt):
    start = nt[u]
    for v in range(start, n):
        nt[u] = v + 1
        if m[u][v]:
            return v
    return -1


def dfs_visit(r, m, n, color, d, f):
    nt = [0] * n
    stack = [r]
    color[r] = GRAY
    global tt
    tt += 1
    d[r] = tt

    while len(stack) != 0:
        u = stack[-1]
        v = next(u, m, n, nt)
        if v != -1:
            if color[v] == WHITE:
                color[v] = GRAY
                tt += 1
                d[v] = tt
                stack.append(v)
        else:
            stack.pop()
            color[u] = BLACK
            tt += 1
            f[u] = tt


def dfs(n, m):
    color = [WHITE] * n
    d = [-1] * n
    f = [-1] * n
    global tt
    tt = 0
    for u in range(n):
        if color[u] == WHITE:
            dfs_visit(u, m, n, color, d, f)
    for i in range(n):
        print('{0} {1} {2}'.format(i+1, d[i], f[i]))



n = int(input())
m = [[False] * n for i in range(n)]
for i in range(n):
    line = [int(v) for v in input().split()]
    u = line[0] - 1
    for v in line[2:]:
        v -= 1
        m[u][v] = True

dfs(n, m)

Python: 
def DFS(n = 1, A = [0], i = 0, d = [0], f = [0], time = 1):
    for j in range(n):
        if A[i][j] == 1 and d[j] == 0:
            time = time + 1
            d[j] = time
            DFS(n, A, j, d, f, time)
        time = time + 1
        f[i] = time

n = int(raw_input())
A = [0] * n
for i in range(n):
    A[i] = [0] * n

for i in range(n):
    value = map(int, raw_input().split())
    u = value[0] - 1
    k = value[1]
    nodes = value[2:]
    for i in range(k):
        v = nodes[i] - 1
        A[u][v] = 1

d = [0] * n
f = [0] * n
time = 1
d[0] = time
DFS(n, A, 0, d, f, time)

for i in range(n):
    print(str(i + 1) + " " + str(d[0]) + " " + str(f[0]))