Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	G := make([][]int, N)
	for i := 0; i < N; i++ {
		u, k := sc.nextInt()-1, sc.nextInt()
		for j := 0; j < k; j++ {
			G[u] = append(G[u], sc.nextInt()-1)
		}
	}
	ans := make([][2]int, N)
	time := 0
	found := make(map[int]bool)
	var dfs func(cur int)
	dfs = func(cur int) {
		time++
		ans[cur][0] = time
		found[cur] = true
		for i := 0; i < len(G[cur]); i++ {
			next := G[cur][i]
			if !found[next] {
				dfs(G[cur][i])
			}
		}
		time++
		ans[cur][1] = time
	}
	for i := 0; i < N; i++ {
		if !found[i] {
			dfs(i)
		}
	}

	for i := 0; i < N; i++ {
		fmt.Fprint(wtr, i+1)
		for j := 0; j < 2; j++ {
			fmt.Fprint(wtr, " ")
			fmt.Fprint(wtr, ans[i][j])
		}
		fmt.Fprintln(wtr)
	}
	wtr.Flush()
}

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

using namespace std;

int n, u, k, v, t;
int adjList[101][101];
int adjNum[101];
bool visited[101];

int d[101], f[101];

void dfs(int u) {
    if (visited[u]) return;
    visited[u] = true;

    d[u] = t;
    t++;

    for (int i = 0; i < adjNum[u]; ++i) {
        dfs(adjList[u][i]);
    }

    f[u] = t;
    t++;

}

int main () {
	scanf("%d", &n);

    for (int i = 0; i < n; ++i) {
        scanf("%d %d", &u, &k);
        adjNum[u-1] = k;
        for (int j = 0; j < k; ++j) {
            scanf("%d", &v);
            adjList[u-1][j] = v-1; // all IDs start from 1
        }
    }

    t = 1;
    for (int u = 0; u < n; ++u) {
        dfs(u);
        cout << u+1 << " " << d[u] << " " << f[u] << "\n";
    }

	return 0;
}

C++: #include <iostream>
#include<stack>
using namespace std;
const int MAXn=100;

int n,M[MAXn][MAXn]={0},nt[MAXn],col[MAXn];//color:0=white,1=gray,2=brack
int d[MAXn],f[MAXn],t;

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 u)
{
	stack<int> S;
	S.push(u);
	col[u]=1;
	d[u]=++t;
	while(!S.empty())
	{
		int v=S.top();
		int r=next(v);
		if(r!=-1)
		{
			if(col[r]==0)
			{
				col[r]=1;
				d[r]=++t;
				S.push(r);
			}
		}
		else
		{
			S.pop();
			col[v]=2;
			f[v]=++t;
		}
	}
	return;
}

void dfs()
{
	int u;
	for(u=0;u<n;u++)
	{
		col[u]=0;
		nt[u]=0;
	}
	t=0;
	
	for(u=0;u<n;u++)if(col[u]==0)dfs_visit(u);
	
	for(u=0;u<n;u++)cout<<u+1<<" "<<d[u]<<" "<<f[u]<<endl;
	
	return;
}

int main() {
	cin>>n;
	int id,k,v;
	for(int i=0;i<n;i++)
	{
		cin>>id>>k;
		id--;
		for(int j=0;j<k;j++)
		{
			cin>>v;
			M[id][--v]=1;
		}
	}
	dfs();
	return 0;
}

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

using namespace std;
int graph[125][125], color[125], times, s[125], f[125], v, w, n;
class DFS{
public:
	static void search(){
		for(int i = 1;i<=n;i++){
			color[i] = 0;
		}
		times = 0;
		for(int u = 1;u<=n;u++){
			if(color[u] == 0){
				visit(u);
			}
		}
	}
	static void visit(int u){
		color[u] = 1;
		s[u] = ++times;
		for(int w=1;w<=n;w++){
			if(graph[u][w] == 0) continue;
			if(color[w] == 0){
				visit(w);
			}
		}
		color[u] = 2;
		f[u] = ++times;
	}
};
int main(){
	cin >> n;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n;j++){
			graph[i][j] = 0;
		}
	}

	for(int i=1;i<=n;i++){
		int num;
		int k;
		int tmp;
		cin >> num >> k;
		if(k !=0){
			for(int j=0;j<k;j++){
				cin >> tmp;
				graph[num][tmp] = 1;
			}
		}
	}
	DFS::search();
	int i;
	for(i=1;i<=n;i++){
		cout << i << " " << s[i] << " " << f[i] << endl;
	}
}

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

using namespace std;

int main(){
    stack<int> st;
    int n;
    cin >> n;
    int d[n] = {};
    int f[n] = {};
    int vnum[n][2] = {};
    bool vflag[n] = {};
    int tmp2;
    int num;
    vector<vector<int>> vertex;
    vector<int> tmp;
    for(int i=0;i<n;i++){
        cin >> num;
        cin >> num;
        vnum[i][0] = num;
        for(int j=0;j<num;j++){
            cin >> tmp2;
            tmp.push_back(tmp2);
        }
        vertex.push_back(tmp);
        tmp.clear();
    }
    int cnt = 1;
    bool check;
    int s;
    st.push(0);
    do{
        s = st.top();

        if(((vnum[s][0]==0) && d[s]==0) || (s==vertex[s][vnum[s][1]]-1)){
            vflag[s] = true;
            d[s] = cnt++;
            f[s] = cnt++;
            st.pop();
        }else if(vnum[s][0]==vnum[s][1]){
            vflag[s] = true;
            f[s] = cnt++;
            st.pop();
        }else if((vflag[vertex[s][vnum[s][1]]-1]) && (d[s]==0)){
            if(vnum[s][0]-vnum[s][1]==1){
                vflag[s] = true;
                d[s] = cnt++;
                f[s] = cnt++;
                st.pop();
            }else{
                vnum[s][1]++;
            }
        }else if(vflag[vertex[s][vnum[s][1]]-1]){
            vflag[s] = true;
            f[s] = cnt++;
            st.pop();
        }else if(vflag[s]){
            st.push(vertex[s][vnum[s][1]++] - 1);
        }else{
            if(d[s]==0){
                d[s] = cnt++;
            }
            st.push(vertex[s][vnum[s][1]++] - 1);
            if(vnum[s][0]==vnum[s][1]){
                vflag[s] = true;
            }
            if(vflag[vertex[s][vnum[s][1]]-1]){
                f[s] = cnt++;
                st.pop();
            }
        }
        check = !st.empty();
        if(!check){
            for(int i=0;i<n;i++){
                if(vflag[i]==false){
                    check = true;
                    st.push(i);
                    break;
                }
            }
        }
    }while(check);

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

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

int n;
int M[100][100];
int color[100], d[100], f[100];
int t;

void Dfs(int u) {
  color[u] = 1;
  d[u] = ++t;
  for (int v = 0; v < n; v++) if (M[u][v] && color[v] == 0) Dfs(v);
  color[u] = 2;
  f[u] = ++t;
}

int main() {
  cin >> n;

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

  Dfs(0);

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

  return 0;
}