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<utility>
using namespace std;
vector<int> l[101];
int matrix[100][100];
pair<int,int> t[101];
bool visited[101];
int tim=0;
void dfs(int cur)
{
    tim+=1;
    t[cur].first=tim;
    //cerr<<"visiting "<<cur<<' '<<tim<<endl;
    visited[cur]=true;
    
    for(int i=0;i<l[cur].size();i++)
    {
        if((matrix[cur-1][l[cur][i]-1]==1)&&(visited[i]==false))
        {
            dfs(l[cur][i]);
        }
    }
    
    tim+=1;
    t[cur].second=tim;
    
    
}
int main()
{
    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 tmp;
            cin>>tmp;
            l[u].push_back(tmp);
        }
    }
    
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n;j++)
        {
            matrix[i][j]=0;
        }
    }
    for(int i=1;i<n+1;i++)
    {
        visited[i]=false;
        for(int j=0;j<l[i].size();j++)
        {
            matrix[i-1][l[i][j]-1]=1;
        }
    }
    
    for(int i=1;i<n+1;i++)
    {
        if(visited[i]==false)
            dfs(i);
    }
    
    for(int i=1;i<n+1;i++)
    {
        cout<<i<<" "<<t[i].first<<" "<<t[i].second<<endl;
    }
}

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

using std::cin;
using std::cout;

struct vertex {
    int vv;
    int ww;
};

//enum class VColor {White, Gray, Black};
typedef enum {White, Gray, Black} VColor;

void
dfsearch(std::vector<vertex> *gar, int gsz, int uu,
         std::vector<VColor> &color,
         std::vector<int> &dd, std::vector<int> &ff, std::vector<int> &prev,
         int &cnt)
{
    color[uu] = Gray;
    dd[uu] = ++cnt;
    //cout << uu << " " << cnt << std::endl;
    std::vector<vertex>::iterator it = gar[uu].begin();
    for (; it != gar[uu].end(); it++) {
        int     vv = (*it).vv;
        if (color[vv] == White) {
            prev[vv] = uu;
            dfsearch(gar, gsz, vv, color, dd, ff, prev, cnt);
        }
    }
    
    color[uu] = Black;
    ff[uu] = ++cnt;
    return;
}

int
main()
{
    int vn;
    std::vector<vertex> gar[100 + 1];

    cin >> vn;
    for (int idx = 0; idx < vn; idx++) {
        int uu;
        int kk;
        int vv;

        cin >> uu >> kk;
        for (int ik = 0; ik < kk; ik++) {
            cin >> vv;
            gar[uu].push_back({vv, 1});
        }
    }

#if 0
    for (int uu = 1; uu <= vn; uu++) {
        std::vector<vertex>::iterator it = gar[uu].begin();
#if 0
        for (; it != gar[uu].end(); it++) {
            printf("v = %d w = %d\n", (*it).vv, (*it).ww);
        }
#else
        for (int vv = 1; vv <= vn; vv++) {
            if (vv != 1) cout << ' ';
            if ((it != gar[uu].end()) && ((*it).vv == vv)) {
                cout << '1';
                it++;
            } else {
                cout << '0';
            }
        }
        cout << std::endl;
#endif
    }
#endif

    std::vector<VColor> color;
    std::vector<int> dd;
    std::vector<int> ff;
    std::vector<int> prev;
    int counter;

    color.assign(vn + 1, White);
    dd.assign(vn + 1, 0);
    ff.assign(vn + 1, 0);
    prev.assign(vn + 1, 0);

    counter = 0;
    dfsearch(gar, vn, 1, color, dd, ff, prev, counter);
    std::vector<VColor>::iterator cit = color.begin();
    for (cit++; cit != color.end(); cit++) {
        if (*cit == White) {
            dfsearch(gar, vn, std::distance(color.begin(), cit), color,
                     dd, ff, prev, counter);
        }
    }

    for (int uu = 1; uu <= vn; uu++) {
        cout << uu << " " << dd[uu] << " " << ff[uu] << std::endl;
    }
}

C++: #include"bits/stdc++.h"
using namespace std;

struct Node {
	int in, out;
	bool flag = false;
	vector<int> v;
};

int dfs(vector<Node>& u, int id, int d)
{
	if (u[id].flag) return d - 1;

	int a;
	u[id].in = d;
	u[id].flag = true;
	for (int i = 0; i < u[id].v.size(); i++)
	{
		d = dfs(u, u[id].v[i], d + 1);

	}
	u[id].out = d + 1;
	return d + 1;
}

int main(void)
{
	int N, id, k, x;
	Node z;
	cin >> N;
	vector<Node> u(N + 1);
	for (int i = 0; i < N; i++)
	{
		cin >> id >> k;
		for (int j = 0; j < k; j++)
		{
			cin >> x;
			u[id].v.push_back(x);
		}
	}

	int d = 0;
	for(int i = 1; i <= N; i++) d = dfs(u, i, d + 1);

	for (int i = 1; i <= N; i++) cout << i  << " " << u[i].in << " " <<  u[i].out << endl;

	return 0;
}

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

vector<int> graph[100];
int d[100], f[100];
int visited = 0;

void dfs(int id){
    d[id] = visited++;
    for(int i = 0; i < graph[id].size(); i++)
	{
        if(graph[id][i] != id && !d[graph[id][i]] && !f[graph[id][i]])
		{
			dfs(graph[id][i]);
		}
    }
    f[id] = visited++;
}

int main(){
    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;
            graph[u - 1].push_back(v - 1);
        }
    }
    dfs(0);
    for(int i = 0;i < n;i++)
	{
        if(!f[i]) 
		{
			dfs(i);
		}
    }
    for(int i = 0;i < n;i++)
	{
        cout << i + 1 << " " << d[i] << " " << f[i] << endl;
    }
    return 0;
}