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 <stdio.h>
#include <stdint.h>
#include <iostream>
#include <fstream>
#include <cassert>
#include <climits>

#include <vector>
#include <memory>
using namespace std;

#define DEBUG (1)
#define USE_UNIQUE_PTR (1)

#if DEBUG
#define DPRINTF(...) do { \
    printf("D(L%d) %s: ", __LINE__, __func__); \
    printf(__VA_ARGS__); \
  } while (false)
#else
#define DPRINTF(...)
#endif // DEBUG

int g_num = -1;
int g_time = 1;

class Vertex {
public:
  Vertex() :
    id_(-1),
    discover_time_(-1),
    finish_time_(-1),
    adjacentNum_(0),
#if USE_UNIQUE_PTR
    adjacentIds_(nullptr),
#endif
    isVisited_(false) { }

  ~Vertex() {
  }

  void setAdjacency(const vector<int> &adjacentIds);

  inline void setId(int id) { id_ = id; }
  inline void setDiscoverTime(int time) { discover_time_ = time; }
  inline void setFinishTime(int time) { finish_time_ = time; }
  inline void setVisited(bool visited) { isVisited_ = visited; }

  inline int getId() { return id_; }
  inline int getDiscoverTime() { return discover_time_; }
  inline int getFinishTime() { return finish_time_; }
  inline bool getVisited() { return isVisited_; }
  inline int getAdjacentNum() { return adjacentNum_; }
  inline int getAdjacentId(int idx) {
    if (adjacentIds_ == nullptr || idx > adjacentNum_)
      return -1;
    return adjacentIds_[idx];
  }

  void printTime();
  void printAdj();

private:
  int id_;
  int discover_time_;
  int finish_time_;

  int adjacentNum_;
#if USE_UNIQUE_PTR
  unique_ptr<int[]> adjacentIds_;
#else
  static const int kMaxId = 100;
  int adjacentIds_[kMaxId];
#endif // USE_UNIQUE_PTR

  bool isVisited_;
};


void Vertex::setAdjacency(const vector<int> &adjacentIds)
{
#if USE_UNIQUE_PTR
  if (adjacentIds_) assert(1);
#endif // USE_UNIQUE_PTR

  adjacentNum_ = adjacentIds.size();
#if USE_UNIQUE_PTR
  adjacentIds_ = unique_ptr<int[]>(new int[adjacentNum_]);
#endif // USE_UNIQUE_PTR

  for (int i = 0; i < adjacentNum_; i++)
  {
    adjacentIds_[i] = adjacentIds[i];
  }

}

void Vertex::printTime()
{
  printf("%d %d %d\n", id_, discover_time_, finish_time_);
}

void Vertex::printAdj()
{
  DPRINTF("%d %d", id_, adjacentNum_);
  for (int i = 0; i < adjacentNum_; i++) {
    printf(" %d", adjacentIds_[i]);
  }
  cout << endl;
}


void dfs(Vertex vertices[], int idx)
{

  DPRINTF("time %d  idx %d\n", g_time, idx);

  assert(idx <= g_num);

  Vertex &vtx = vertices[idx];

  if (vtx.getVisited())
    return ;

  vtx.setVisited(true);
  vtx.setDiscoverTime(g_time);
  g_time++;

  for (int i = 0; i < vtx.getAdjacentNum(); i++)
  {
    int id = vtx.getAdjacentId(i);
    dfs(vertices, id);
  }

  vtx.setFinishTime(g_time);
  g_time++;
}


int main()
{
  cin >> g_num; cin.ignore();
  DPRINTF("Node num %d\n", g_num);

  Vertex vertices[g_num+1];

  for (int i = 1; i <= g_num; i++)
  {
    int id;
    int num;

    cin >> id >> num;
    vertices[i].setId(id);
    DPRINTF("node %d (num %d)\n", id, num);

    vector<int> adjs;

    for (int j = 0; j < num; j++)
    {
      int adj;
      cin >> adj;

      adjs.push_back(adj);
    }

    if (adjs.size())
      vertices[i].setAdjacency(adjs);

    cin.ignore();
  }

#if DEBUG
  for (int i = 1; i <= g_num; i++) vertices[i].printAdj();
#endif

  for (int i = 1; i <= g_num; i++)
    if (!vertices[i].getVisited())
      dfs(vertices, i);

  for (int i = 1; i <= g_num; i++) vertices[i].printTime();

  return 0;
}

C++: #include <bits/stdc++.h>
#define be(v) (v).begin(),(v).end()
#define pb(q) push_back(q)
typedef long long ll;
using namespace std;
const ll mod=1000000007;
#define doublecout(a) cout<<fixed<<setprecision(10)<<a<<endl;
int ans=0,a[100],b[100];
bool niko[100];
vector<vector<int> > v(100);
void dfs(int n){
	if(a[n])return;
	a[n]=++ans;
	for(auto& i:v[n])dfs(i);
	b[n]=++ans;
	return;
}
int main() {
    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(false);
    memset(a,0,sizeof(a));
    int n;
    cin>>n;
    int k,c;
    for(int i=0;i<n;i++){
    	cin>>c>>k;
    	for(int j=0;j<k;j++){
    		cin>>c;
    		v[i].pb(--c);
    	}
    }
    for(int i=0;i<n;i++)sort(be(v[i]));
    for(int i=0;i<n;i++)dfs(i);
    for(int i=0;i<n;i++){
    	cout <<i+1<<" "<<a[i]<<" "<<b[i]<<endl; 
    }
    return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define repR(i, n) for(int i = (n) - 1; i > -1; i--)
#define rep1(i, n) for(int i = 1; i < (int)(n + 1); i++)
#define rep1R(i, n) for(int i = (n); i > 0; i--)
using namespace std;

const int WHITE = 0;
const int GRAY = 1;
const int BLACK = 2;

int n;
int M[110][110] = {};
int color[110];
int elapse = 0;
int d[110];
int f[110];

void dfs(int u) {
  color[u] = GRAY;
  d[u] = ++elapse;
  rep(v, n) {
    if (M[u][v] && color[v] == WHITE) dfs(v);
  }
  color[u] = BLACK;
  f[u] = ++elapse;
}

void dfs_init() {
  rep(i, n) color[i] = WHITE;
  rep(i, n) {
    if (color[i] == WHITE) dfs(i);
  }
}

int main() {
  cin >> n;
  rep(i, n) {
    int id, deg;
    cin >> id >> deg;
    --id;    // 0-indexedに直す
    rep(j, deg) {
      int v;
      cin >> v;
      --v;    // 0-indexedに直す
      ++M[id][v];
    }
  }
  dfs_init();
  rep(i, n) {
    cout << i + 1 << " " << d[i] << " " << f[i] << endl;
  }
  return 0;
}