Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

var infty = 1000000000

type nodeKey int

type DirectedGraphNode struct {
	key       nodeKey
	adjacents []*DirectedGraphNode
	visited   bool
	d         int
	f         int
	parent    *DirectedGraphNode
}

type DirectedGraph struct {
	nodes []*DirectedGraphNode
}

func (g *DirectedGraph) setAdjacency(l, r nodeKey) {
	g.nodes[l].adjacents = append(g.nodes[l].adjacents, g.nodes[r])
}

func newDirectedGraph(nNodes int) *DirectedGraph {
	graph := DirectedGraph{}
	graph.nodes = make([]*DirectedGraphNode, nNodes)
	for iNodes := 0; iNodes < nNodes; iNodes++ {
		graph.nodes[iNodes] = &DirectedGraphNode{}
		graph.nodes[iNodes].key = nodeKey(iNodes)

		graph.nodes[iNodes].visited = false
		graph.nodes[iNodes].d = infty
		graph.nodes[iNodes].f = infty
		graph.nodes[iNodes].parent = nil
	}
	return &graph
}

type QueueEntry struct {
	node *DirectedGraphNode
	next *QueueEntry
}

type Queue struct {
	head, tail *QueueEntry
}

func (q *Queue) enqueue(node *DirectedGraphNode) {
	entry := QueueEntry{}
	entry.node = node

	if q.tail == nil {
		q.head = &entry
		q.tail = &entry
		return
	}

	q.tail.next = &entry
	q.tail = q.tail.next
}

func (q *Queue) dequeue() *QueueEntry {
	if q.head == nil {
		return nil
	}
	poped := q.head
	q.head = q.head.next
	if q.head == nil {
		q.tail = nil
	}
	return poped
}

func (q *Queue) isEmpty() bool {
	return q.head == nil
}

var time = 0

func fillDistancesByDepthFirstSearch(g *DirectedGraph) {
	for _, u := range g.nodes[1:] {
		if !u.visited {
			dfsVisit(g, u)
		}
	}
}

func dfsVisit(g *DirectedGraph, u *DirectedGraphNode) {
	time++
	u.d = time

	u.visited = true
	for _, v := range u.adjacents {
		if !v.visited {
			v.parent = u
			dfsVisit(g, v)
		}
	}
	time++
	u.f = time
}

func main() {
	scanner.Split(bufio.ScanWords)

	nNodes := nextInt()
	g := newDirectedGraph(nNodes + 1)

	for iNode := 0; iNode < nNodes; iNode++ {
		nodeKeyLeft := nodeKey(nextInt())
		nAdj := nextInt()
		for iAdj := 0; iAdj < nAdj; iAdj++ {
			nodeKeyRight := nodeKey(nextInt())
			g.setAdjacency(nodeKeyLeft, nodeKeyRight)
		}
	}

	fillDistancesByDepthFirstSearch(g)

	for iNode := 1; iNode <= nNodes; iNode++ {
		node := g.nodes[iNode]
		fmt.Println(node.key, node.d, node.f)
	}
}

C++: #include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <stack>
#include <list>
#include <queue>
#include <deque>
#include <algorithm>
#include <numeric>
#include <utility>
#include <complex>
#include <functional>
#include <climits>

using namespace std;
vector<int> v[101];
int d[101] = {0};
int f[101] = {0};
int t = 0;
void dfs(int id) {
    //d mark
    d[id] = t;
    t++;
    for(int adj: v[id]) {
        if(d[adj] == 0) {
            dfs(adj);
            t++;
        }
    }
    f[id] = t;
}

int main() {
    int n;
    cin >> n;
    for(int i=1; i<=n; i++) {
        int u, k;
        cin >> u >> k;
        for(int j=0; j<k; j++) {
            int adj;
            cin >> adj;
            v[i].push_back(adj);
        }
    }
    for(int i=1; i<=n; i++) {
        if(d[i] == 0) {
            t++;
            dfs(i);
        }
    }

    for(int i=1; i<=n; i++) {
        cout << i << " " << d[i] << " " << f[i] << endl;
    }
}

C++: #include <bits/stdc++.h>
//#define int long long

using namespace std;
using LL = long long;
using P = pair<int, int>;

#define FOR(i, a, n) for(int i = (int)(a); i < (int)(n); ++i)
#define REP(i, n) FOR(i, 0, n)

#define pb(a) push_back(a)
#define all(x) (x).begin(),(x).end()

const int INF = (int)1e9;
const LL INFL = (LL)1e19;
const int MOD = 1e9 + 7;

using Graph = vector<vector<int>>;

int dfs(Graph &graph, vector<int> &d, vector<int> &f, int cur, int time)
{
    if(d[cur] > 0) return time;
    d[cur] = time;
    time++;
    for(int child : graph[cur])
    {
        time = dfs(graph, d, f, child, time);
    }
    f[cur] = time;
    time++;
    return time;
}

signed main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    int n;
    cin >> n;
    Graph graph(n);
    REP(i, n) 
    {
        int u, k;
        cin >> u >> k;
        REP(j, k) 
        {
            int v;
            cin >> v;
            graph[u-1].push_back(v-1);
        }
    }

    vector<int> d(n, 0), f(n, 0);
    int time = 1;
    REP(i, n)
    {
        if(d[i] > 0) continue;
        time = dfs(graph, d, f, i, time);
    }

    REP(i, n)
    {
        cout << i+1 << " " << d[i] << " " << f[i] << endl;
    }
}

C++: #include<iostream>
using namespace std;

int G[101][102];
int found[101];
int comp[101];   // complete.
int t;  // time.

typedef struct box{ int val; box* next; } box_t;  // stack.

box_t* init()
{
    box_t* head = new box_t;
    head->val = -1;
    head->next = NULL;
    return head;
}

bool isEmpty(box_t* head){ return (head->next == NULL ? true : false); }

box_t* push(box_t* head, int data)
{
    box_t* box = new box_t;
    box->val = data;
    box->next = head->next;
    head->next = box;
    return box;
}

int pop(box_t* head)
{
    if(isEmpty(head)){ return -1; }
    box_t* box = head->next;
    int val;
    head->next = box->next;
    val = box->val;
    delete box;
    return val;
}

int front(box_t* head)
{
    int val;
    if(isEmpty(head)){ return -1; }
    val = head->next->val;
    return val;
}

box_t* stack = init();

void search_loop(int i)
{
    int j, k;
    while(1){
        if(found[i] == 0){
            t++; found[i] = t;
            push(stack, i);
        }
        for(k = G[i][0]; G[i][k] != 0 && found[G[i][k]] != 0; k++);
        if(G[i][k] == 0){
            if(isEmpty(stack)){ return; }
            else{
                j = pop(stack);
                t++; comp[j] = t;
                i = front(stack);
            }
        }else{
            G[i][0] = k + 1;
            i = G[i][k];
        }
    };
    return;
}

int main()
{
    int n, i, j, a, b, e;
    cin >> n;
    for(i = 1; i <= n; i++){
        G[i][0] = 1;
        for(j = 1; j <= n + 1; j++){ G[i][j] = 0; } }

    for(i = 1; i <= n; i++){
        cin >> a >> e;
        for(j = 1; j <= e; j++){
            cin >> b; G[a][j] = b; } }  // adjacent representation.

    for(i = 1; i <= n; i++){ found[i] = 0; comp[i] = 0; }
    t = 0;
    while(1){
        for(i = 1; i <= n; i++){
            if(found[i] == 0) break;
        }
        if(i > n) break;
        search_loop(i);
    };

    for(i = 1; i <= n; i++){
        cout << i << " " << found[i] << " " << comp[i] << endl;
    }
    return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;

struct Graph{
	
	vector<char> seen;
	vector<vector<int>> e;
	vector<int> time1,time2; 
	Graph(int n) : seen(n),e(n),time1(n),time2(n){}
	
	void dfs(int v, int &t){
		t++;
		time1.at(v) = t;
		seen.at(v) = 1;
		for(auto nv:e.at(v)) {
			if(seen.at(nv)==1) continue;
			dfs(nv,t);
		}
		t++;
		time2.at(v) = t;
		return;
	}
	
};

int main() {
	
	int n;
	cin >> n;
	Graph graph(n);
	for(int i=0; i<n; i++){
		int u,k;
		cin >> u >> k;
		for(int j=0; j<k; j++){
			int v;
			cin >> v;
			v--;
			graph.e.at(i).push_back(v);
		}
	}
	
	int t={};
	for(int i=0; i<n; i++){
		if(graph.seen.at(i)!=1) graph.dfs(i,t);
	}
	
	for(int i=0; i<n; i++){
		cout << i+1 << ' ' << graph.time1.at(i) << ' ' << graph.time2.at(i) << endl;
	}
	
	
}