Go: package main

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

type TimeRecord struct {
	discoverTime int
	finishTime   int
}

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

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

	timeRecordMap := make([]TimeRecord, n)
	childrenMap := make([][]int, n)
	for i := 1; i <= n; i++ {
		node, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		timeRecordMap[node-1] = TimeRecord{-1, -1}

		childNum, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		childrenMap[node-1] = make([]int, childNum)
		for j := 0; j < childNum; j++ {
			child, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			childrenMap[node-1][j] = child
		}
	}

	timer := 1
	startNode := 1
	for {
		visit(startNode, &timer, childrenMap, timeRecordMap)
		startNode = findStartNode(childrenMap, timeRecordMap)
		if startNode < 0 {
			break
		}
	}
	for k, v := range timeRecordMap {
		fmt.Printf("%d %d %d\n", k+1, v.discoverTime, v.finishTime)
	}
}

func findStartNode(childrenMap [][]int, timeRecordMap []TimeRecord) int {
	x := -1
	for node, timeRecord := range timeRecordMap {
		if timeRecord.discoverTime < 0 {
			x = node + 1
			break
		}
	}
	return x
}

func visit(currentNode int, timer *int, childrenMap [][]int, timeRecordMap []TimeRecord) {
	if timeRecordMap[currentNode-1].discoverTime > 0 {
		return
	}
	children := childrenMap[currentNode-1]
	timeRecordMap[currentNode-1] = TimeRecord{*timer, timeRecordMap[currentNode-1].finishTime}
	(*timer)++
	for i := 0; i < len(children); i++ {
		visit(children[i], timer, childrenMap, timeRecordMap)
	}
	timeRecordMap[currentNode-1] = TimeRecord{timeRecordMap[currentNode-1].discoverTime, *timer}
	(*timer)++
}

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

C++: #include <bits/stdc++.h>
using namespace std;
struct Fast {
    Fast() {
        cin.tie(0);
        ios::sync_with_stdio(false);
        cout << fixed << setprecision(20);
    }
} fast;

void yes() {
    cout << "Yes" << endl;
    exit(0);
}
void no() {
    cout << "No" << endl;
    exit(0);
}
#define REP(i, n) for (long long i = 0; i < (n); i++)

long long modpow(long long m, long long n) {
    if (n == 0) return 1;
    if (n % 2 == 0) {
        long long t = modpow(m, n / 2);
        return t * t % 2019;
    } else {
        return modpow(m, n - 1) * m % 2019;
    }
}
long long n;
vector<bool> visited(100, false);
vector<int> t1(100);
vector<int> t2(100);
vector<vector<long long>> graph(100);
int ts = 1;
void dfs(int cur) {
    visited[cur] = true;
    t1[cur] = ts;
    ts++;
    for (int i = 0; i < graph[cur].size(); i++) {
        if (visited[graph[cur][i]] == false) {
            dfs(graph[cur][i]);
        }
    }
    t2[cur] = ts;
    ts++;
}
signed main() {
    cin >> n;
    for (long long i = 0; i < n; i++) {
        long long s, k;
        cin >> s >> k;
        for (int j = 0; j < k; j++) {
            int l;
            cin >> l;
            graph[s - 1].push_back(l - 1);
        }
    }
    REP(i, n) {
        if (!visited[i]) {
            dfs(i);
        }
    }
    REP(i, n) { cout << i + 1 << " " << t1[i] << " " << t2[i] << endl; }
}

C++: #include<stdio.h>
#include<stdlib.h>
#define N 102
#define white 0
#define gray 1
#define black 2

int n,color[N],d[N],f[N],S[N],top=0,t=0,nt[N],a[N][N];

void push(int x){
  if(top==N){
    printf("Stack overflow!\n");
    exit(2);
  }
  S[++top]=x;
}

int pop(void){
  if(top==0){
    printf("Stack is empty!\n");
    exit(3);
  }
  top--;
  return S[top+1];
}

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

void dfs(int r){
  int i;
  for(i=1;i<=n;i++) nt[i]=0;

  push(r);
  color[r]=gray;
  d[r]=++t;

  while(S[top]!=0){
    int u=S[top],v=next(u);

    if(v!=-1){
    if(color[v]==white){
      color[v]=gray;
      d[v]=++t;
      push(v);
    }
    }
    else {
      pop();
      color[u]=black;
      f[u]=++t;
    }
  }
}

void dfs_init(){
  int i,u;
  for(i=1;i<=n;i++){
    color[i]=white;
  }
  t=0;

  for(u=1;u<=n;u++){
    if(color[u]==white) dfs(u);
  }

}

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

int main(){
  int i,j,u,k,v;

  scanf("%d",&n);
  for(i=1;i<=n;i++){
    for(j=1;j<=n;j++){
      a[i][j]=0;
    }
  }

  for(i=1;i<=n;i++){
    scanf("%d%d",&u,&k);
    for(j=1;j<=k;j++){
      scanf("%d",&v);
      a[u][v]=1;
    }
  }

  dfs_init();
  print();


  return 0;
}

C++: #include<iostream>
#include<vector>
using namespace std;
int cnt=1;
void depth(vector< vector<int> > &vv,vector<int> &f,vector<int> &c,int num){
	f[num]=cnt;
	cnt++;
	for(int i=0; i<vv[num].size(); i++){
		if(vv[num][i]!=0 && f[i]==0){
			depth(vv,f,c,i);
		}
	}
	if(c[num]==0){
		c[num]=cnt;
		cnt++;
	}
}
int main(){
	int n;
	cin>>n;
	vector< vector<int> > v(n,vector<int> (n,0));
	vector<int> ft(n,0);
	vector<int> ct(n,0);
	int u[n];
	for(int i=0; i<n; i++){
		int k;
		cin>>u[i]>>k;
		for(int j=0; j<k; j++){
			int x;
			cin>>x;
			v[i][x-1]=1;
		}
	}
	for(int i=0; i<n; i++){
		if(ft[i]==0){
			depth(v,ft,ct,i);
		}
	}
	for(int i=0; i<n; i++){
		cout<<u[i]<<" "<<ft[i]<<" "<<ct[i]<<endl;
	}
  return 0;
}

C++:  #include<stdio.h>
#define Gray 0
#define White 1
#define Black 2
int time;
int d[101],f[101],color[101],Adj[101][101];  
int n;

void DFS_Visit(int u){
  int i;  
  color[u]=Gray;
  d[u]=++time;
  for(i=1;i<=n;i++){
    if(color[i]==White && Adj[u][i]==1) DFS_Visit(i);
  }
  color[u]=Black;
  f[u]=++time;
}

void DFS(){
  int i;
  for(i=1;i<=n;i++){
    color[i]=White;
  }
  time=0;
  for(i=1;i<=n;i++){
    if(color[i]==White) DFS_Visit(i);
}
}

main(){
  
  int k,i,j,t,g;

  scanf("%d",&n);
    for(i=0;i<=n;i++){
      for(j=0;j<=n;j++){
	Adj[i][j]=0;
      }
    } 
    
    for(i=1;i<=n;i++){
      scanf("%d",&g);    
      scanf("%d",&k);
      for(j=1;j<=k;j++){
	scanf("%d",&t);
	Adj[g][t]=1;   
      }
    } DFS();
    
    for(i=1;i<=n;i++){
   
      printf("%d %d %d\n",i,d[i],f[i]);
    }
    return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
using Graph = vector<vector<int>>;

vector<bool> seen;
vector<int> first_order; // 行きがけ順
vector<int> last_order; // 帰りがけ順
void dfs(const vector<vector<int>> &G,int v,int& ptr){
  first_order[v] = ptr++;

  // vを訪問済みにする
  seen[v] = true;

  // vから行ける各頂点next_vについて
  for(auto next_v:G[v]){
    if(seen[next_v]) continue;
    dfs(G,next_v,ptr);
  }

  last_order[v] = ptr++;
}

int main(){
  //頂点数
  int n;
  cin >> n;

  Graph G(n+1);
  //頂点番号、隣接頂点数、隣接頂点番号
  for(int i=1;i<=n;i++){
    int u,k;
    cin >> u >> k;
    for(int j=0;j<k;j++){
      int v;
      cin >> v;
      G[u].push_back(v);
    }
  }

  seen.assign(n+1,false);
  first_order.resize(n+1);
  last_order.resize(n+1);
  int ptr = 1;
  for(int i=1;i<=n;i++){
    if(seen[i]) continue;
    dfs(G,i,ptr);
  }

  // 各頂点vの行きがけ順、帰りがけ順を出力
  for(int v = 1;v<=n;v++){
    cout << v << " " << first_order[v] << " " << last_order[v] << endl;
  }
}