Go: package main

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

type vertexId int

type vertex struct {
	id vertexId
	firstVisitAt int
	finishVisitAt int
	adjs []vertexId
}

func createVertex(id int, adjsInt []int) vertex {
	adjs := make([]vertexId, len(adjsInt))
	for i := 0; i < len(adjs); i++ {
		adjs[i] = vertexId(adjsInt[i])
	}
	return vertex{
		id: vertexId(id),
		firstVisitAt: 0,
		finishVisitAt: 0,
		adjs: adjs,
	}
}

func (v *vertex) isVisited() bool {
	return v.firstVisitAt > 0
}

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	currentVertex := &vertices[currentId-1]
	if currentVertex.isVisited() {
		return timestamp
	}
	timestamp = timestamp + 1
	currentVertex.firstVisitAt = timestamp
	for _, adjId := range currentVertex.adjs {
		timestamp = dfs(adjId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

func solveDfs(vertices []vertex) {
	timestamp := 0
	for {
		vid := vertexId(-1)
		for i := 0; i < len(vertices); i++ {
			if !vertices[i].isVisited() {
				vid = vertexId(i+1)
				break
			}
		}
		if vid > 0 {
			timestamp = dfs(vid, timestamp, vertices)
		} else {
			break
		}
	}
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	vertices := make([]vertex, n)
	for i := 0; i < n; i++ {
		id, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjN, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjs := make([]int, adjN)
		for j := 0; j < adjN; j++ {
			adjId, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			adjs[j] = adjId
		}
		vertices[i] = createVertex(id, adjs)
	}

	solveDfs(vertices)

	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", vertices[i].id, vertices[i].firstVisitAt, vertices[i].finishVisitAt)
	}
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

func nextInt(sc *bufio.Scanner) (int, error) {
	return strconv.Atoi(nextText(sc))
}

C++: #include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)

int main(){
	int n;
	cin>>n;
	vector<vector<int> > A(n);//????????????????????????-1?????\???????????????
	//??\???
	REP(i,n){
		int u,k;
		cin>>u>>k;
		A[i]=vector<int>(k,0);
		REP(j,k){
			int l;
			cin>>l;
			A[i][j] = l-1;
		}
	}
	//??¢?´¢
	vector<int> s;//??????????????????????????\???
	vector<int> dis(n,0);//??????????????????????????????
	vector<int> fin(n,0);//???????????????????????????
	int time=0;
	while(find(dis.begin(),dis.end(), 0) != dis.end()){
		int saisyo = find(dis.begin(),dis.end(), 0) -  dis.begin();
		//cout<<saisyo<<endl;
		s.push_back(saisyo);//?????????0???????????????
		while(!s.empty()){
		//REP(ss,3){
			int k = s.back();//??????????????????????????????
			if(dis[k]==0){
				time++;
				dis[k]=time;
				//cout<<"dis "<<k<<" / time "<<time<<endl;
			}
			bool isfinish=true;
			for(int i: A[k]){
				//cout<<"?????????"<<i<<endl;
				bool nai = find(s.begin(),s.end(), i) == s.end();
				if(fin[i]==0 && i!=k && nai){
					s.push_back(i);
					isfinish=false;
					break;
				}
			}
			if(isfinish){
				time++;
				fin[k]=time;
				s.pop_back();
				//cout<<"fin "<<k<<" / time "<<time<<endl;
			}
		}
	}
	REP(i,n){
		cout<<i+1<<" "<<dis[i]<<" "<<fin[i]<<endl;
	}
	return 0;
}

C++: #include<iostream>

using namespace std;
typedef long long ll;

const int MAX = 100;

static int u[MAX][MAX];
static int d[MAX];
static int f[MAX];
static int v[MAX];


void seekNode(int n, int& elp) {

	d[n] = elp;
	elp++;
	v[n] = 1;

	for (int i = 0;i < MAX;i++) {
		if (u[n][i] > 0 && v[i] == 0) {
			seekNode(i, elp);
		}
	}


	f[n] = elp;
	elp++;
	return;
}


int main() {

	int n, uid, ap, tmp, elp;
	cin >> n;


	for (int i = 0;i < n;i++) {
		cin >> uid >> ap;
		for (int k = 0;k < ap;k++) {
			cin >> tmp;
			u[uid - 1][tmp - 1] = 1;
		}
	}
	elp = 1;
	for (int i = 0;i < n;i++) {
		if (v[i] == 0)	seekNode(i, elp);
	}

	for (int i = 0;i < n;i++) {
		cout << i + 1 << ' ' << d[i] << ' ' << f[i] << endl;
	}


	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;
//Graph I - Depth First Search
//http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_11_B

#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

//WHITE -> ????¨?????????????
//GRAY  -> ?¨????????????????(?¨?????????????????¨???????????????????????????????????????§???????????????)
//BLACK -> ?¨??????????????????????(????¨???????????????????????????????????????????)

int n, M[N][N];
int color[N];//?????????????¨??????¶???
int d[N];//????????????
int f[N];//????????????
int tt;//time stamp

//?????°???????????±???????????¢?´¢
void dfs_visit( int u )
{
	int v;
	color[u] = GRAY;
	d[u] = ++tt;//??????????¨????
	for( 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()
{
	//??¨???????????????color???WHITE????¨????
	for( int u = 0; u < n; u++ ) color[u] = WHITE;
	tt = 0;
	for( int u = 0; u < n; u++ ){
		//????¨??????? u ?????°??????????§?????????¨????????±???????????¢?´¢
		if( color[u] == WHITE ) dfs_visit( u );
	}
	for( int u = 0; u < n; u++ ){
		cout << u + 1 << " " << d[u] << " " << f[u] << endl;
	}
}
int main()
{
	int u;//???????????????
	int k;//??????u?????£??\?????????????????????
	int v;//??????u????¬???°

	cin >> n;

	for( int i = 0; i < n; i++ ){
		for( int j = 0; j < n; j++ ){
			M[i][j] = 0;
		}
	}
	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();
	return 0;
}

C++: #include <stdio.h>
#include <iostream>
#include <utility>
#include <algorithm>
#include <math.h>
#include <vector>
#include <list>

using namespace std;
int n;
list<int> adj[101];
int d[101] = {};
int f[101] = {};

void DFS(int v)
{
    static int num = 1;
    d[v] = num++;
    while (!adj[v].empty())
    {
        if (d[adj[v].front()] == 0)
            DFS(adj[v].front());
        adj[v].pop_front();
    }
    f[v] = num++;
}

void print()
{
    for (int i = 1; i <= n; i++)
    {
        printf("%d %d %d\n", i, d[i], f[i]);
    }
}

int main()
{
    int u, k, v;
    cin >> n;

    for (int i = 0; i < n; i++)
    {
        cin >> u >> k;
        while (k > 0)
        {
            cin >> v;
            adj[u].push_back(v);
            k--;
        }
    }

    DFS(1);

    print();

    return 0;
}

C++: #include<bits/stdc++.h>
#define REP(i,n) for(long long i=0;i<n;++i)
#define FOR(i,a,b) for(long long i=a;i<b;++i)
using namespace std;
int n,graph[101][101],visit[101];
int d[101],f[101],t;
const int WHITE=0;
const int GRAY=1;
void dfs(int u){
    visit[u]=GRAY;
    d[u]=++t;
    FOR(v,1,n+1){
        if(graph[u][v]==0) continue;
        if(visit[v]==WHITE) dfs(v);
    }
    f[u]=++t;
    //printf("%d %d %d\n",u,d[u],f[u]);
}
int main(){
    int u,k,v;
    scanf("%d",&n);
    REP(i,n){
        scanf("%d%d",&u,&k);
        REP(j,k){
            scanf("%d",&v);
            graph[u][v]=1;
        }
    }
    FOR(i,1,n+1){
        if(visit[i]==WHITE) dfs(i);
    }
    FOR(i,1,n+1){
        printf("%d",i);
        printf(" %d %d\n",d[i],f[i]);
    }
    return 0;
}