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 <cstdio>
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <typeinfo>
#include <numeric>
#include <functional>
#include <unordered_map>
#include <bitset>
#include <stack>


using namespace std;
using ll = long long;
using ull = unsigned long long;

const ll INF = 1e16;
const ll MOD = 1e9 + 7;

#define REP(i, n) for(ll i = 0; i < n; i++)






vector<vector<ll>> g;
vector<bool> used;
vector<vector<ll>> ans;
ll t;

void dfs(ll v){
    used[v] = true;
    ans[v][0] = ++t;
    for(auto &x : g[v]){
        if(!used[x])dfs(x);
    }
    ans[v][1] = ++t;
}


int main() {
    ll n;
    cin >> n;
    g.resize(n);
    REP(i, n){
        ll u, k;
        cin >> u >> k;
        u--;
        REP(j, k){
            ll v;
            cin >> v;
            v--;
            if(v >= 0) g[u].push_back(v);
        }
    }
    
    used.assign(n, false);
    ans.resize(n, vector<ll>(2));
    REP(i, n) if(!used[i]) dfs(i);
    REP(i, n){
        cout << i + 1 << " " << ans[i][0] << " " << ans[i][1] << endl;
    }
}

C++: #include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <cctype>
#include <string>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <algorithm>
#include <functional>

using namespace std;
using ll = long long int;
#define rep(i,n) for(int i = 0; i < n; i++)
#define FOR(i, a, b)  for(int i = (a); i < (b) ; i++)

#define pb push_back
#define SORT(v,n) sort(v, v+n)
#define ALL(x) (x).begin(),(x).end()
#define debug(x) cerr << #x << ": " << x << '\n'
#define elif else if
#define itn ll
#define int ll
const int INF = 100100100;
const int MOD = (int)1e9 + 7;
const double EPS = 1e-9;
///                →,↑,←,↓,↗,↖,↙,↘
int dx[8] = { 1, 0, -1, 0, 1, -1, -1, 1 };
int dy[8] = { 0, 1, 0, -1, 1, 1, -1, -1 };

static const int N = 100;
static const int White = 0;
static const int Gray = 1;
static const int Black = 2;
int d[N], f[N],tt;
int color[N],n,M[N][N];
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 u) {
	stack<int> S;
	S.push(u);
	color[u] = Gray;
	d[u] = ++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 {
			color[u] = Black;
			S.pop();
			f[u] = ++tt;
		}
	}
}

void dfs() {
	int u;
	rep(u, n)color[u] = White;
	rep(u, n) {
		if (color[u] == White) dfs_visit(u);
	}
	rep(u, n) {
		cout << u + 1 << ' ' << d[u] << ' ' << f[u] << '\n';
	}
}

signed main() {
	ios::sync_with_stdio(false);
	cin >> n;
	int i;
	rep(i, n) {
		int u, k, v;
		cin >> u >> k;
		u--;
		int j;
		rep(j, k) {
			cin >> v;
			v--;
			M[u][v] = 1;
		}
	}
	dfs();
	return 0;
}

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

#define MAX 105

struct Point{
    int id;
    int d;
    int f;
    bool flag;
    std::vector<int> child;
};

int stack[MAX];
int sp = 0;
int count = 1;

Point p[MAX];

void push(int id){
    if(p[id].flag == false){
        stack[sp++] = id;
        p[id].d = count++;
        p[id].flag = true;
    }
}

void pop(){
    p[stack[--sp]].f = count++;
    //return stack[sp];
}

void dft(int id){
    std::cout << id << "に対しdft\n";
    push(id);
    int size = p[id].child.size();
    for(int i=0;i<size;i++){
        if(p[p[id].child[i]].flag == false){
            dft(p[id].child[i]);
        }
    }
    pop();
}

int main(){
    int n;
    int size;
    std::cin >> n;
    for(int i=1;i<=n;i++){
        std::cin >> p[i].id >> size;
        for(int j=0;j<size;j++){
            int tmp;
            std::cin >> tmp;
            p[i].child.push_back(tmp);
        }
    }
    for(int i=1;i<=n;i++){
        if(p[i].flag == false){
            dft(i);
        }
    }
    
    for(int i=1;i<=n;i++){
        std::cout << p[i].id << ' ' << p[i].d << ' ' << p[i].f << '\n';
    }
    
    return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define ll long long 

vector<vector<int>> graph;
vector<int> d,f;
int tm =0;

void dfs(int v){
      if(d[v]!=0) return;
      tm++;
      d[v]=tm;

      for(int i=0;i<graph[v].size();i++){
            dfs(graph[v][i]);
      }
      tm++;
      f[v] = tm;
}

int main(){ 
      int n; cin>>n;
      graph.resize(n); d.assign(n,0); f.resize(n);
      for(int i=0;i<n;i++){
            int u,k; cin>>u>>k;
            if(k==0) continue;
            for(int j=0;j<k;j++){
                  int v; cin >> v;
                  graph[u].push_back(v-1);
            }
      }
      for(int i=0;i<n;i++){
            dfs(i);
      }
      for(int i=0;i<n;i++){
            cout << i+1 << " " << d[i] << f[i] << endl;
      }
      
}