Go: package main

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

type vertexId int

type vertex struct {
	id vertexId
	firstVisitAt int
	finishVisitAt int
	adjs []vertexId
}

func createVertex(id int, adjsInt []int) vertex {
	adjs := make([]vertexId, len(adjsInt))
	for i := 0; i < len(adjs); i++ {
		adjs[i] = vertexId(adjsInt[i])
	}
	return vertex{
		id: vertexId(id),
		firstVisitAt: 0,
		finishVisitAt: 0,
		adjs: adjs,
	}
}

func (v *vertex) doesAllAdjsVisited(vertices []vertex) bool {
	for _, vId := range v.adjs {
		adj := vertices[vId-1]
		if !adj.isVisited() {
			return false
		}
	}
	return true
}

func (v *vertex) isFirstVisit() bool {
	return v.firstVisitAt == 0
}

func (v *vertex) isVisited() bool {
	return v.firstVisitAt > 0
}

func (v *vertex) nextVertex(vertices []vertex) (vertexId, error) {
	for _, vId := range v.adjs {
		adj := vertices[vId-1]
		if !adj.isVisited() {
			return vId, nil
		}
	}
	return vertexId(-1), fmt.Errorf("illegal")
}

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	timestamp = timestamp + 1
	currentVertex := &vertices[currentId-1]
	if currentVertex.isFirstVisit() {
		currentVertex.firstVisitAt = timestamp
	}
	for !currentVertex.doesAllAdjsVisited(vertices) {
		nextVertexId, _ := currentVertex.nextVertex(vertices)
		timestamp = dfs(nextVertexId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

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

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

	vertices := make([]vertex, n)
	for i := 0; i < n; i++ {
		id, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjN, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjs := make([]int, adjN)
		for j := 0; j < adjN; j++ {
			adjId, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			adjs[j] = adjId
		}
		vertices[i] = createVertex(id, adjs)
	}

	dfs(vertexId(1), 0, vertices)

	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", vertices[i].id, vertices[i].firstVisitAt, vertices[i].finishVisitAt)
	}
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

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

C++: #include <cstdio>
#include <iostream>
#include <stack>
#define MAX_VERTEXES 100
#define ZERO 0
#define NIL -1

using namespace std;

//think easy make easy

int n;//num of vertexes(頂点)
int matrix_graph[MAX_VERTEXES+1+1][MAX_VERTEXES+1+1];//1オリジン

stack<int> stk;
bool discovered[MAX_VERTEXES+1+1];//1オリジン
int discovered_time[MAX_VERTEXES+1+1];
int completed_time[MAX_VERTEXES+1+1];
int current_time = 0;

void DFS(int v){
	int v_tmp;
	for(int i=1;i<=n;i++){
		//if(i == v);
		if(matrix_graph[v][i] == 1 && !discovered[i]){
			current_time++;
			discovered_time[i] = current_time;
			stk.push(v);
			matrix_graph[v][i] == 0;
			discovered[i] = true;
			DFS(i);
		}else if(matrix_graph[v][i] == 1 && discovered[i]){
			matrix_graph[v][i] == 0;
		}

		if(i == n){
			current_time++;
			completed_time[v] = current_time;
			//if(!stk.empty())
			//{
				//cout <<stk.top() <<endl;
				//v_tmp = stk.top();
				//stk.pop();
				//DFS(v_tmp);
			//}
		}
	}
}

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

	int v_num;
	int k;//v_numの出次数

	for(int i=1;i<=n;i++){
		for(int j=1;j<=n;j++){
			matrix_graph[i][j] = ZERO;
		}
	}

	for(int i=0;i<n;i++){
		scanf("%d",&v_num);
		scanf("%d",&k);

		for(int j=0;j<k;j++){
			int v_num2;
			scanf("%d",&v_num2);
			matrix_graph[v_num][v_num2] = 1;
		}
	}

	for(int i=1;i<=n;i++){
		discovered[i] = false;
		discovered_time[i] = NIL;
		completed_time[i] = NIL;
	}

	for(int i=1;i<=n;i++){
	//	cout <<"c" <<current_time <<" ";
		//current_time++;//ここではなく
		if(!discovered[i]){
			current_time++;//ココ
			//cout <<i <<endl;
			discovered[i] = true;
			discovered_time[i] = current_time;
			DFS(i);
		}
	}

	for(int i=1;i<=n;i++){
		cout <<i <<" " <<discovered_time[i] <<" " <<completed_time[i] <<endl;
	}

	return 0;
}

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

enum Status {WHITE, GRAY, BLACK};

stack<int> stc;
Status *status;
int *discovered, *finished;
vector<vector<int>> a;
int n, timer;

void dfs(int i){
        if(status[i]==BLACK) return;
        if(status[i]==WHITE){
                discovered[i] = ++timer;
                status[i] = GRAY;
        }
        stc.push(i);

        for(int j=0;j<a[i].size();j++) dfs(a[i][j]);

        if(status[i]==GRAY){
                finished[i] = ++timer;
                status[i] = BLACK;
        }
        stc.pop();
}

int main(){

        cin>>n;
        a = vector<vector<int>>(n, vector<int>());
        status = new Status[n];
        discovered = new int[n];
        finished = new int[n];

        int m, k, r;
        for(int i=0;i<n;i++){
                cin>>r;
                cin>>m;
                for(int j=0;j<m;j++){
                        cin>>k;
                        a[r-1].emplace_back(k-1);
                }
        }
        for(int i=0;i<n;i++) status[i] = WHITE;

        timer = 0;
        dfs(0);


        for(int i=0;i<n;i++){
                cout<<i+1<<" "<<discovered[i]<<" "<<finished[i]<<endl;
        }
        return 0;
}

C++: #include<iostream>
using namespace std;
#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

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

void visit(int r){
  color[r] = GRAY;
  d[r] = ++t;
  for(int v=0;v<n;v++){
    if(M[r][v] == 0) continue;
    if(color[v] == WHITE) visit(v);
  }
  color[r] = BLACK;
  f[r] = ++t;
}


void dfs(){
  for(int u=0;u<n;u++) color[u] = WHITE;
  t = 0;

  for(int u=0;u<n;u++){
    if(color[u] == WHITE) visit(u);
  }

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

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

  cin >> n;
  for(int i=0;i<n;i++){
    for(int j=0;j<n;j++) M[i][j] = 0;
  }

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

  dfs();
  
  return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<string>
#include<algorithm>
#include<cstring>
#include<vector>
#include<stack>
using namespace std;
#define INT(x) int x; scanf("%d",&x)
#define INPUT(x) scanf("%d",&x)
#define REP1(x,n) for(int x = 0; x < n; x++)
#define REP2(x,s,e) for(int x = s; x <= e; x++)
#define BR printf("\n")
#define INF 2000000000

vector<int> V[100];//0 origin
bool complete[100] = {};
stack<int> S;
int time_ = 1;
int NodeStump[100][2];//find,end

void DFS(){
    NodeStump[S.top()][0] = time_;
    time_++;//d++
    if (S.empty()) return;
    
    REP1(i,V[S.top()].size()){
        if (!complete[V[S.top()][i]]){
            S.push(V[S.top()][i]);
            DFS();
        }
    }
    
    complete[S.top()] = true;
    NodeStump[S.top()][1] = time_;
    S.pop();
    time_++;//d--
}

int main(){
    INT(N);
    
    REP1(i,N){
        int from,n;
        scanf("%d %d",&from,&n);
        REP1(j,n){
            INT(to);
            V[i].push_back(to - 1);
        }
    }
    
    S.push(0);
    
    DFS();
    
    REP1(i,N){
        printf("%d %d %d\n",i+1,NodeStump[i][0],NodeStump[i][1]);
    }
    
    return 0;
}