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: n = int(input())
G = [[] for _ in range(n)]
u1 = 0
for _ in range(n):
    u, k, *v = [int(i) for i in input().split()]
    G[u - 1] = v
    if k != 0 and u1 == 0:
        u1 = u

time = 1
u = u1
D = []
F = []
out = [[i+1, 0, 0] for i in range(n)]
T = []
while True:
    if u not in D:
        out[u - 1][1] = time
        D.append(u)
        T.append(u)

    for f in F:
        if f in G[u - 1]:
            idx = G[u - 1].index(f)
            del G[u - 1][idx]

    if G[u - 1] == []:
        time += 1
        out[T.pop() - 1][2] = time
        F.append(u)
        if T == []:
            if len(D) == n:
                break
            else:
                for ni in range(n):
                    if ni + 1 not in D:
                        u = ni + 1
                        break
        else:
            u = T[-1]
    else:
        u = G[u - 1].pop(0)
        time += 1

for ni in range(n):
    print(*out[ni])

Python: count = 0


def solve(i, a, ans):
    global count
    if ans[i][0] == 0:
        count += 1
        ans[i][0] = count

    for x in range(a[i][1]):
        if ans[a[i][2 + x] - 1][0] == 0:
            solve(a[i][2 + x] - 1, a, ans)

    if ans[i][1] == 0:
        count += 1
        ans[i][1] = count


N = int(input())
a = []
for _ in range(N):
    a.append([int(x) for x in input().split()])

ans = [[0 for i in range(2)] for j in range(N)]

for i in range(N):
    if ans[i][0] == 0:
        solve(i, a, ans)

for i, x in enumerate(ans):
    print(i + 1, *x)

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

import sys

UNVISITED, VISITED_IN_STACK, POPPED_OUT = 0, 1, 2


def generate_adj_matrix(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)

        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)
        else:
            vertex_visit_stack.pop()
            vertex_status_list[current_vertex] = POPPED_OUT
            time += 1
            vertex_f_time[current_vertex] += time

    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_matrix(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())
graph = [-1] + [list(map(int, input().split())) for _ in range(n)]
seen = [False]*(n+1)
seen[0] = True
d = [-1]*(n+1)
f = [-1]*(n+1)
time = 0


def dfs(v):
    global time
    time += 1
    d[v] = time
    seen[v] = True
    k = graph[v][1]
    if k > 0:
        for i in range(k):
            w = graph[v][i+2]
            if seen[w] is False:
                dfs(w)
    
    time += 1
    f[v] = time

v = 0
while v <= n:
    if seen[v] is False:
        dfs(v)
    
    v += 1

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