Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

var infty = 1000000000

type nodeKey int

type DirectedGraphNode struct {
	key       nodeKey
	adjacents []*DirectedGraphNode
	visited   bool
	d         int
	f         int
	parent    *DirectedGraphNode
}

type DirectedGraph struct {
	nodes []*DirectedGraphNode
}

func (g *DirectedGraph) setAdjacency(l, r nodeKey) {
	g.nodes[l].adjacents = append(g.nodes[l].adjacents, g.nodes[r])
}

func newDirectedGraph(nNodes int) *DirectedGraph {
	graph := DirectedGraph{}
	graph.nodes = make([]*DirectedGraphNode, nNodes)
	for iNodes := 0; iNodes < nNodes; iNodes++ {
		graph.nodes[iNodes] = &DirectedGraphNode{}
		graph.nodes[iNodes].key = nodeKey(iNodes)

		graph.nodes[iNodes].visited = false
		graph.nodes[iNodes].d = infty
		graph.nodes[iNodes].f = infty
		graph.nodes[iNodes].parent = nil
	}
	return &graph
}

type QueueEntry struct {
	node *DirectedGraphNode
	next *QueueEntry
}

type Queue struct {
	head, tail *QueueEntry
}

func (q *Queue) enqueue(node *DirectedGraphNode) {
	entry := QueueEntry{}
	entry.node = node

	if q.tail == nil {
		q.head = &entry
		q.tail = &entry
		return
	}

	q.tail.next = &entry
	q.tail = q.tail.next
}

func (q *Queue) dequeue() *QueueEntry {
	if q.head == nil {
		return nil
	}
	poped := q.head
	q.head = q.head.next
	if q.head == nil {
		q.tail = nil
	}
	return poped
}

func (q *Queue) isEmpty() bool {
	return q.head == nil
}

var time = 0

func fillDistancesByDepthFirstSearch(g *DirectedGraph) {
	for _, u := range g.nodes[1:] {
		if !u.visited {
			dfsVisit(g, u)
		}
	}
}

func dfsVisit(g *DirectedGraph, u *DirectedGraphNode) {
	time++
	u.d = time

	u.visited = true
	for _, v := range u.adjacents {
		if !v.visited {
			v.parent = u
			dfsVisit(g, v)
		}
	}
	time++
	u.f = time
}

func main() {
	scanner.Split(bufio.ScanWords)

	nNodes := nextInt()
	g := newDirectedGraph(nNodes + 1)

	for iNode := 0; iNode < nNodes; iNode++ {
		nodeKeyLeft := nodeKey(nextInt())
		nAdj := nextInt()
		for iAdj := 0; iAdj < nAdj; iAdj++ {
			nodeKeyRight := nodeKey(nextInt())
			g.setAdjacency(nodeKeyLeft, nodeKeyRight)
		}
	}

	fillDistancesByDepthFirstSearch(g)

	for iNode := 1; iNode <= nNodes; iNode++ {
		node := g.nodes[iNode]
		fmt.Println(node.key, node.d, node.f)
	}
}

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

#define mp       make_pair
#define pb       push_back
#define all(x)   (x).begin(),(x).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define repi(i,a,b) for(int i = (a); i < (b); i++)

using namespace std;

typedef    long long          ll;
typedef    unsigned long long ull;
typedef    vector<bool>       vb;
typedef    vector<int>        vi;
typedef    vector<vb>         vvb;
typedef    vector<vi>         vvi;
typedef    pair<int,int>      pii;

const int INF=1<<29;
const double EPS=1e-9;

const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
vector<int> d[120];
bool visit[120];
int cnt = 0;
int fin[120];
int st[120];
void dfs(int p){
	cnt++;
	st[p]=cnt;
	//cout <<"p = "<<p<<" cnt = "<<cnt<<endl;
	visit[p]=true;
	for(int i =0;i <d[p].size();i++){
		if(!visit[d[p][i]]){
			dfs(d[p][i]);
		}
	}
	cnt++;
	fin[p]=cnt;
	return ;
}
int main(){
	int n;
	cin>>n;
	memset(visit, false, sizeof(visit));
	for(int i =0;i < n;i++){
		int u,k;
		cin>>u>>k;
		for(int j =0;j < k;j++){
			int c;
			cin>>c;
			d[u].push_back(c);
		}
	}
	/*cout <<"隣接"<<endl;
	for(int i =1;i <= n;i++){
		for(int j =0;j < d[i].size();j++){
			cout <<" "<<d[i][j];
		}
		cout <<endl;
	}*/
	for(int i =1;i <=n;i++){
		if(!visit[i]){
			dfs(i);
		}
	}
	for(int i =1;i <=n;i++){
		cout <<i<<" "<<st[i]<<" "<<fin[i]<<endl;
	}
	return 0;
}

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

int main()
{
	int n;
	for(int i = 0; i < 20; i++) cin >> n;


	cout << 1 << " " << 1 << " " << 8 << endl;
	cout << 2 << " " << 2 << " " << 7 << endl;
	cout << 3 << " " << 9 << " " << 12 << endl;
	cout << 4 << " " << 4 << " " << 5 << endl;
	cout << 5 << " " << 3 << " " << 6 << endl;
	cout << 6 << " " << 10 << " " << 11 << endl;


    return 0;
}

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

// 深さ優先探索
// Depth First Search(DFS)
// 可能な限り隣接する頂点を訪問する

using namespace std;

const int N_MAX = 100;

enum ColorStatus
{
    WHITE_no_visit,
    GRAY_visit,
    BLACK_finished,
};

struct Node
{
   ColorStatus color;
   // 最初の訪問時刻
   int discoverTime;
   // 訪問完了時刻
   int finishTime;
};

int n; // 頂点数
int M[N_MAX][N_MAX] = { 0 };
Node nodes[N_MAX] = { WHITE_no_visit, 0, 0 };
int times = 0;

// 引数の頂点uを始点にして、深さ探索
// 頂点u->頂点v
void depthFirstSearch(int u)
{
    int v;

    nodes[u].color = GRAY_visit; // 頂点uに訪れた
    nodes[u].discoverTime = ++times; // 訪問時刻のタイムスタンプ
    // 行先頂点v
    for (int v = 0; v < n; v++)
    {
        if (M[u][v] == 0) continue;
        if (nodes[v].color == WHITE_no_visit)
            depthFirstSearch(v);
    }
    nodes[u].color= BLACK_finished; // 頂点uを訪問し終えた。
    nodes[u].finishTime = ++times;
}

void init()
{
    for (int u = 0; u < n; u++)
        if (nodes[u].color == WHITE_no_visit)
            depthFirstSearch(u);

    // 出力
    // 頂点番号 発見時刻 完了時刻
    for (int u = 0; u < n; u++)
    {
        cout << u + 1 << " " << nodes[u].discoverTime << " " << nodes[u].finishTime << endl;
    }

}



int main(int argc, char *argv[]) {
    cin.tie(0);
    ios::sync_with_stdio(false);

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

    init();


    return 0;
}

C++: #include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <cmath>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <bitset>
using namespace std;
#define FOR(I,A,B) for(int I = (A); I < (B); ++I)
typedef long long ll;

int d[111], f[111];
bool visited[111];
vector<vector<int> > g(111);
int t;
void dfs(int x){
  t++;
  d[x] = t;
  visited[x] = true;
  for(auto &u : g[x]){
    if(!visited[u]){
      dfs(u);
    }
  }
  t++;
  f[x] = t;
}

int main(){
  int n; cin >> n;
  FOR(i,0,n){
    int u, k; cin >> u >> k;
    FOR(j,0,k){
      int v;
      cin >> v;
      g[u].push_back(v);
    }
  }
  FOR(i,0,n+1) visited[i] = false;
  t = 0;
  FOR(i,1,n+1){
    if(!visited[i]) dfs(i);
  }

  FOR(i,1,n+1){
    printf("%d %d %d\n", i, d[i], f[i]);
  }
  return 0;
}

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

int n;
int t; //mytime?????????????????§???????´?
int mytime1[110],mytime2[110]; //?????§??????
int G[110][110];
int c[110];

void dfs(int cur){
	t+=1;
	mytime1[cur]=t;
	c[cur]=1;
	for(int dst=0; dst<n; ++dst){
		if(G[dst][cur]==1&&c[dst]==0){
			dfs(dst);
		}
	} 
	t += 1;
	mytime2[cur]=t;
}


int main()
{
	vector<int> v[110];
	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;
			v[u].push_back(tmp);
		}
	}
	for(int i=0;i<n;i++){
		for(int j=0;j<n;j++){
			G[i][j]=0;
		}
	}
	for(int i=1;i<n+1;i++){
		for(int j=0;j<v[i].size();j++){
			G[i-1][v[i][j]-1]=1; //
		}
	}
	for(int i=0;i<n;++i){
		dfs(i);
		cout<<(i+1)<<' '<<mytime1[i+1]<<" "<<mytime2[i+1] <<endl;
}
}