Go: package main

import (
	"fmt"
)

func main() {
	var n int
	fmt.Scan(&n)
	g := make([][]int, n+1)
	for i := 0; i < n; i++ {
		var u,k int
		fmt.Scan(&u)
		fmt.Scan(&k)
		g[u] = make([]int, k)
		for j := 0; j < k; j++ {
			fmt.Scan(&g[u][j])
		}
	}

	d := make([]int, n+1)
	f := make([]int, n+1)
	t := 1
	for i := 1; i <= n; i++ {
		t = dfs(&g, &d, &f, i, t)
	}

	for i := 1; i <= n; i++ {
		fmt.Printf("%d %d %d\n", i, d[i], f[i])
	}
}

func dfs(g *[][]int, d *[]int, f *[]int, id int, t int) int {
	if (*d)[id] > 0 {
		return t
	}
	(*d)[id] = t
	t += 1
	for i := 0; i < len((*g)[id]); i++ {
		t = dfs(g, d, f, (*g)[id][i], t)
	}
	(*f)[id] = t
	return t+1
}

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

import sys

UNVISITED, VISITED_IN_STACK, POPPED_OUT = 0, 1, 2


def generate_adj(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)
        # print('start', current_vertex, next_vertex, vertex_status_list, vertex_visit_stack)

        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)
                # print('on', current_vertex, next_vertex, vertex_status_list, vertex_visit_stack)
        else:
            # print('no out degree', current_vertex)
            vertex_visit_stack.pop()
            vertex_status_list[current_vertex] = POPPED_OUT
            time += 1
            vertex_f_time[current_vertex] += time
        # print('end', current_vertex, vertex_status_list, vertex_visit_stack)

    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(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())
G = []
for i in range(n):
    T = [0]*n
    G.append(T)
for i in range(n):
    L = list(map(int,input().split()))
    for j in range(2,len(L)):
        G[i][L[j]-1] += 1
time = 1
D = [-1]*n
F = [-1]*n
def dfs(src):
    global time
    D[src] = time
    time += 1
    for dst in range(n):
        if G[src][dst] == 1 and D[dst] == -1:
            dfs(dst)
    F[src] = time
    time += 1
for root in range(n):
    if D[root] == -1:
        dfs(root)
for i in range(n):
    print(i+1,D[i],F[i])

Python: # -*- coding: utf-8 -*-

def DFS_stack(adj, start):
    n = len(adj)
    d = [0] * n
    f = [0] * n
    flag = [0] * n # 0:????¨????, 1:?¨??????????, 2:?¨??????????
    S = []
    time = 1

    S.append(start)
    flag[start] = 1
    d[start] = time
    time = time + 1
    
    while flag.count(2) != n: # ??¨????????????????????¢?´¢????????????????????§
        if len(S) != 0:
            u = S.pop()
            v = [i for i, x in enumerate(adj[u]) if (x == 1) and (flag[i] == 0)] 
            # v := ??£??\???????????????????????¢?´¢??????????????????
            if len(v) != 0:
                S.append(u)
                S.append(v[0])
                flag[v[0]] = 1
                d[v[0]] = time
                time = time + 1
            else:
            #??£??\??????????????¨????¨??????????
                flag[u] = 2
                f[u] = time
                time = time + 1

        else:
        	#??????????????????????????£?????´????????¢?´¢??????????????????????????¢?´¢????§?
            u = flag.index(0)
            S.append(u)
            flag[u] = 1
            d[u] = time
            time = time + 1            

    return d, f    

def DFS(adj, start):
    
    n = len(adj)
    d = [0] * n
    f = [0] * n
    flag = [0] * n
    time = 1
    
    def DFS_recursive(u, time):
        #print(u, flag)
        flag[u] = 1
        d[u] = time
        time = time + 1
        v = [i for i, x in enumerate(adj[u]) if x == 1]
        for i in v:
            if flag[i] == 0:
                time = DFS_recursive(i, time)
        flag[u] = 2
        f[u] = time
        time = time + 1
        return time
        
    time = DFS_recursive(start, time)
    for i in range(n):
        if flag[i] == 0:
           time =  DFS_recursive(i, time)
    
    return d, f



def main():
    
    n = int(input())
    adj = [[0 for i in range(n)] for j in range(n)]

    for i in range(n):
        tmp = list(map(int, input().split()))
        u = tmp[0]
        u = u -1
        k = tmp[1]
        v = tmp[2:]
        for j in range(k):
            adj[u][v[j]-1] = 1
            
    #d, f = DFS_stack(adj, 0)
    d, f = DFS(adj, 0)
    for i in range(n):
        print(i+1, d[i], f[i])

if __name__ == "__main__":
    main()