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 <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
#define Graph vector<vector<int>>
using namespace std;

void DFS(const Graph &G,int v,vector<bool> &seen,vector<int> &first_order,vector<int> &last_order,int &ptr){//深さ優先探索。
//引数は順にグラフ、始点(注目点)、探索済みかどうか、行きがけでの順番配列、帰りがけでの順番配列、順番カウンタ
//タイムスタンプ型のため、firstとlastでカウンタを共有
  first_order[v]=ptr++;//行きがけのカウント

  seen[v]=true;

  for(auto next_v : G[v]){
    if(seen[next_v]) continue;
    DFS(G,next_v,seen,first_order,last_order,ptr);
  }
  
  last_order[v]=ptr++;//帰りがけのカウント

  return ;

}

 
int main() {

  int n;  cin >> n ;

  Graph G(n+1);//頂点はn個。今回は数値にそのまま対応させるために+1した

  rep(i,n){
    int u,k;
    cin >> u >> k;
    if(k==0) continue;

    rep(j,k){
    int v;
    cin >> v;
    G[u].push_back(v);
    }
  }//入力終了

  vector<bool> seen(n+1,false);
  vector<int> first_order(n+1),last_order(n+1);
  int ptr=1;//今回はカウント1スタート
  for(int i=1;i<=n;i++){
  if(seen[i]) continue;
  DFS(G,i,seen,first_order,last_order,ptr);
  }

  for(int i=1;i<=n;i++){
    cout << i <<' '<< first_order[i] << ' ' << last_order[i] << endl;
  }

  return 0;
}

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

int n, G[101][101], S[101], T[101];

int dfs(int p, int s) {
    if (S[p] != 0) return 0;
    S[p] = s;
    s++;
    for (int i = 0; i < n; i++) {
        if (G[p][i] == 1) {
            s = max(s, dfs(i, s) + 1);
        }
    }
    T[p] = s;
    return s;
}


int main(void) {
    int u, k, v;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> u >> k;
        for (int j = 0; j < k; j++) {
            cin >> v;
            G[u - 1][v - 1] = 1;
        }
    }

    dfs(0, 1);

    for (int i = 0; i < n; i++)
        printf("%d %d %d\n", i + 1, S[i], T[i]);

    return 0;
}

C++: #define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
#define rep(i, n) for(ll i = 0; i < (n); ++i)
#define FOR(i, m, n) for(ll i = m; i < (n); i++)
#define all(x) (x).begin(),(x).end()
using namespace std;
typedef long long ll;
using vi = vector<int>;
using vii = vector<vi>;
using pii = pair<int, int>; 
using vl = vector<ll>;
using vll = vector<vl>;
using pll = pair<ll, ll>;

vector<bool> seen;
vl d, f;

void dfs(ll now, ll &time, vll &G){
    seen[now] = true;
    d[now] = time++;
    for(ll next : G[now]){
        if(seen[next]) continue;
        dfs(next, time, G);
    }
    f[now] = time++;
}

int main() {
    ll N;
    cin >> N;
    vll G(N);
    rep(i, N){
        ll u, k;
        cin >> u >> k;
        u--;
        rep(j, k){
            ll t;
            cin >> t;
            t--;
            G[u].push_back(t);
        }
    }
    seen.assign(N, false);
    d.resize(N);
    f.resize(N);
    ll time = 1;
    rep(i, N){
        if(!seen[i]){
            dfs(i, time, G);
        }
    }
    rep(i, N){
        ll idx = i+1;
        cout << idx << " " << d[i] << " " << f[i] << endl;
    }
}

C++: #include <stdio.h>
#include <iostream>
#include <algorithm>

using namespace std;

int G[101][101];
bool Memo[101];
int d[101];
int f[101];
int count1;

void dfs(int i, int n) {
  if (Memo[i]) {
    count1++;
    d[i] = count1;
    Memo[i] = false;
    for (int j = 0; j < n; j++) {
      if (G[i][j] == 1) {
        dfs(j,n);
      }
    }
    count1++;
    f[i] = count1;
  }
}

int main() {
  int n;
  scanf("%d",&n);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      G[i][j] = 0;
    }
  }
  for (int i = 0; i < n; i++) {
    int row,col;
    scanf("%d %d",&row,&col);
    for (int j = 0; j < col; j++) {
      int d;
      scanf("%d",&d);
      G[row - 1][d - 1] = 1;
    }
  }
  for (int i = 0; i < n; i++) Memo[i] = true;
  count1 = 0;
  dfs(0,n);
  for (int i = 0; i < n; i++) printf("%d %d %d\n",i+1,d[i],f[i]);
  return 0;
}

C++: #include <iostream>
#include <stack>

using namespace std;

#define MAX 110
int num;
int matrix[MAX][MAX];
int dst[MAX];
int counter = 0;
int D[MAX];
int F[MAX];

void input(){
    cin >> num;
    for(int i=0;i<MAX;i++){
        dst[i] = -1;
        for(int j=0;j<MAX;j++){
            matrix[i][j] = 0;
        }
    }
    for(int i=1;i<=num;i++){
        int v; cin >> v;
        int tmp; cin >>tmp;
        for(int j=0;j<tmp;j++){
            int vi; cin >> vi;
            matrix[v-1][vi-1] = 1;
        }
    }
}

void dfs(int cur){
    D[cur] = counter;
    counter++;
    for(int i=0; i< num;i++){
        if(matrix[cur][i] == 1 && D[i]== 0)
            dfs(i);
    }
    F[cur] = counter+1;
    counter++;
    return;
}

int main(){
    input();
    for(int i=0;i<MAX;i++){
        D[i] = 0;
        F[i] = 0;
    }
    dfs(0);
    for(int i=0;i<num;i++){
        cout << i+1 << " " << D[i] << " " << F[i] << endl;
    }
}

C++: #include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define all(v) v.begin(), v.end()
using namespace std;
typedef long long ll;
vector<int> u, d, f; // d はその頂点の発見時刻、f はその頂点の完了時刻
vector<bool> seen;

void dfs(vector<vector<int>> &g, int v, int& ptr) {
	seen[v] = true;
	ptr++;
	d[v] = ptr;
	for(auto next_v: g[v]) {
		if(seen[next_v]) continue;
		dfs(g, next_v, ptr);
	}
	ptr++;
	f[v] = ptr;
}

int main() {
	int n;
	cin >> n;
	vector<vector<int>> g(n);
	u.resize(n);
	d.resize(n);
	f.resize(n);
	seen.assign(n, false);
	rep(i, n) {
		cin >> u[i];
		int k;
		cin >> k;
		rep(j, k) {
			int tmp;
			cin >> tmp;
			tmp--;
			g[i].push_back(tmp);
		}
	}
	int ptr = 0;
	rep(i, n) {
		if(seen[i]) continue;
		dfs(g, i, ptr);
	}
	rep(i, n) {
		printf("%d %d %d\n", u[i], d[i], f[i]);
	}
	return 0;
}