Go: package main

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

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Scan()
	num, _ := strconv.Atoi(sc.Text())
	nodes := make(map[int]*node)

	for i := 0; i < num; i++ {
		sc.Scan()
		id, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		nodeNum, _ := strconv.Atoi(sc.Text())
		n := node{id, make([]int, 0), 0, 0}
		for j := 0; j < nodeNum; j++ {
			sc.Scan()
			nid, _ := strconv.Atoi(sc.Text())
			n.nexts = append(n.nexts, nid)
		}
		nodes[id] = &n
	}

	s := Stack{}
	for i := 1; i < len(nodes)+1; i++ {
		if nodes[i].s != 0 {
			continue
		}
		walk(i, &nodes, s)
	}
	for i := 1; i < len(nodes)+1; i++ {
		fmt.Printf("%v %v %v\n", (*nodes[i]).id, (*nodes[i]).s, (*nodes[i]).e)
	}
}

var time int

func walk(nid int, nodes *map[int]*node, s Stack) {
	n := (*nodes)[nid]
	if n.s != 0 {
		return
	}
	time++
	n.s = time
	s.Push(n)
	for _, v := range n.nexts {
		walk(v, nodes, s)
	}
	time++
	n.e = time
}

type node struct {
	id    int
	nexts []int
	s     int
	e     int
}

// Stack is Stack
type Stack struct {
	stack []interface{}
}

// Push new value
func (stack *Stack) Push(val interface{}) {
	stack.stack = append(stack.stack, val)
}

// Pop new value
func (stack *Stack) Pop() interface{} {
	val := stack.stack[len(stack.stack)-1]
	stack.stack = stack.stack[0 : len(stack.stack)-1]
	return val
}

C++: #include<iostream>
#include<cstdio>
using namespace std;
static const int N=100;
static const int WHITE = 0;
static const int GRAY = 1;
static const int BLACK = 2;
int n,M[N+1][N+1];
int color[N+1],d[N+1],f[N],tt;
void dfs_visit(int u){
    int v;
    color[u]=GRAY;
    d[u]=++tt;
    for(int v=1;v<=n;v++){
        if(M[u][v]==0)continue;
        if(color[v]==WHITE) dfs_visit(v);
    }
    color[u]=BLACK;
    f[u]=++tt;
}
void dfs(){
    for(int u=1;u<=n;u++)color[u]=WHITE;
    tt=0;
    for(int u=1;u<=n;u++){
        if(color[u]==WHITE)dfs_visit(u);
    }
    for(int u=1;u<=n;u++)
        cout<<u<<" "<<d[u]<<" "<<f[u]<<"\n";
}
int main(){
    int u,v,k;
    cin>>n;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++)
            M[i][j]=0;
    }
    for(int i=1;i<=n;i++){
        cin>>u>>k;
        for(int j=1;j<=k;j++){
            cin>>v;
            M[u][v]=1;
            
        }
    }
    dfs();
    return 0;
}

C++: //By Vlgd
#include<bits/stdc++.h>
using namespace std;
int g[101][101]={0},n,vis[101]={0};
int t=0,d[101],f[101];
/*
void dfs(int u){
	d[u]=++t;
	vis[u]=1;
	for(int v=1;v<=n;v++) if (!vis[v]&&g[u][v]==1) dfs(v);
	f[u]=++t;
}*/
stack<int>S;
void dfs2(int i){
	S.push(i); 
	vis[i]=1;
	d[i]=++t;
	while(!S.empty()){
		int u=S.top(),w=-1;
		for (int i=1;i<=n;i++) if (!vis[i]&&g[u][i]==1){w=i;break;}
		if (w!=-1){
			vis[w]=1;
			d[w]=++t;
			S.push(w);
		}
		else{
			f[u]=++t;
			S.pop();
		}
	}
} 
main(){
	int u,v,deg;
	scanf("%d",&n);
	for (int i=0;i<n;i++){
		scanf("%d%d",&u,&deg);
		for (int j=0;j<deg;j++){
			scanf("%d",&v);
			g[u][v]=1;
		}
	}
	for (int i=1;i<=n;i++) if (!vis[i]) dfs2(i);
	for (int i=1;i<=n;i++) printf("%d %d %d\n",i,d[i],f[i]);
}
/*
4
1 1 2
2 1 4
3 0
4 1 3

6
1 2 2 4
2 1 5
3 2 5 6
4 0
5 1 4
6 1 6
*/

C++: #include<iostream>
#include<vector>
using namespace std;
vector<vector<int>> G(100);
vector<pair<int,int>> D(100);
bool visited[100];
int elapse = 1;
void dfs(int x){
    if(visited[x]) return;
    visited[x] = true;
    D[x].first = elapse;
    elapse++;
    for(auto &a:G[x]) dfs(a);
    D[x].second = elapse;
    elapse++;
}
int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N;
    cin>>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;
            G[u-1].push_back(--v);
        }
    }
    dfs(0);
    for(int i=0;i<N;++i) cout<<i+1<<' '<<D[i].first<<' '<<D[i].second<<endl;
}

C++: #include <iostream>
#include<stack>
using namespace std;
static const int N = 100;
static const int WHITE = 0;
static const int GRAY = 1;
static const int BLACK = 2;

int n, M[N][N];
int color[N], d[N], f[N], tt;
int nt[N];

int next(int u) {
	for (int v = nt[u]; v < n; v++) {
		nt[u] = v + 1;
		if (M[u][v])
			return v;
	}
	return -1;
}

void dfs_visit(int r) {
	for (int i = 0; i < n; i++)
		nt[i] = 0;
	stack<int> S;
	S.push(r);
	color[r] = GRAY;
	d[r] = ++tt;
	while (!S.empty()) {
		int u = S.top();
		int v = next(u);
		if (v != -1) {
			if (color[v] == WHITE) {
				color[v] = GRAY;
				d[v] = ++tt;
				S.push(v);
			}
		} else {
			S.pop();
			color[u] = BLACK;
			f[u] = ++tt;
		}
	}
}

void dfs() {
	for (int i = 0; i < n; i++) {
		color[i] = WHITE;
		nt[i] = 0;
	}
	tt = 0;

	for (int u = 0; u < n; u++) {
		if (color[u] == WHITE)
			dfs_visit(u);
	}
	for (int i = 0; i < n; i++) {
		cout << i + 1 << " " << d[i] << " " << f[i] << endl;
	}
}

int main() {
	int u, k, v;
	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 <bits/stdc++.h>
using namespace std;
template<typename T>
ostream& operator<<(ostream& os, const vector<T>& v){
  const char* dlm = "";
  for(const auto& x:v) cout << exchange(dlm, "\t") << x;
  return os;
}
struct Graph{
  size_t time;
  vector<vector<size_t>> v;
  vector<size_t> d,f;
  Graph(size_t n): time(1), v(n), d(n,0), f(n) {}
  void dfs(size_t i){
    d[i]=time++;
    for(const auto& x:v[i]) if(d[x-1]==0) dfs(x-1);
    f[i]=time++;
  }
};
ostream& operator<<(ostream& os, const Graph& x){
  for(size_t i=0; i<x.v.size(); ++i)
    cout<<(i+1)<<' '<<x.d[i]<<' '<<x.f[i]<<'\n';
  return os;
}
int32_t main(){
  size_t n; cin>>n;
  Graph graph(n);
  for(size_t i=0; i<n; ++i){
    size_t id,k; cin>>id>>k;
    graph.v[id-1].resize(k); for(auto&& x:graph.v[id-1]) cin>>x;
  }
  for(size_t i=0; i<n; ++i){
    if(graph.d[i]==0) graph.dfs(i);
  }
  cout<<graph;
}

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

const long N = 100;
const long WHITE = 0;
const long GRAY = 1;
const long BLACK = 2;

long n, M[N + 1][N + 1];
long color[N + 1], d[N + 1], f[N + 1], tt;

void dfs_visit(long u){
	long v;
	color[u] = GRAY;
	d[u] = ++tt;
	for (long v = 1; v <= n; v++){
		if (M[u][v] == 0) continue;
		if (color[v] == WHITE){
			dfs_visit(v);
		}
	}
	color[u] = BLACK;
	f[u] = ++tt;
}

void dfs(){
	for (long u = 1; u <= n; u++) color[u] = WHITE;
	tt = 0;

	for (long u = 1; u <= n; u++){
		if (color[u] == WHITE) dfs_visit(u);
	}
	for (long u = 1; u <= n; u++){
		cout << u << " " << d[u] << " " << f[u] << endl;
	}
}

int main(){
	long u, v, k;

	cin >> n;
	for (long i = 1; i <= n; i++){
		for (long j = 1; j <= n; j++){
			M[i][j] = 0;
		}
	}

	for (long i = 1; i <= n; i++){
		cin >> u >> k;
		for (long j = 1; j <= k; j++){
			cin >> v;
			M[u][v] = 1;
		}
	}

	dfs();

	return 0;
}

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

using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)

typedef long long ll;
typedef pair<int, int> P;

#define MAX 100005
#define INF INT_MAX

int timeStamp = 0;
vector< vector<int> > adj;
vector<int> d, f;

void dfs(int v)
{
    d[v] = ++timeStamp;
    for (auto e : adj[v]) {
        if (d[e]) continue;
        dfs(e);
    }
    f[v] = ++timeStamp;
}

int main(int, char**)
{
    int n;
    cin >> n;

    adj.assign(n, vector<int>());
    d.assign(n,0);
    f.assign(n,0);
    int u, k, v;
    rep(i,n) {
        cin >> u >> k; u--;
        rep(j,k) {
            cin >> v; v--;
            adj[u].push_back(v);
        }
    }
    rep(i,n) {
        if (d[i]) continue;
        dfs(i);
    }
    rep(i,n) {
        cout << i+1 << " " << d[i] << " " << f[i] << endl;
    }
    return 0;
}