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 <bits/stdc++.h>
using namespace std;
#define FOR(i,l,n) for(int i=l; i<(int)(n); ++i)
#define REP(i,n) FOR(i,0,n)
using Graph = vector<vector<int>>;

vector<bool> seen;
vector<int> first_order;
vector<int> last_order;

void dfs(const Graph &G, int v, int& ptr) {

    first_order[v] = ptr++;

    seen[v] = true; 
    for (auto next_v : G[v]) { 
        if (seen[next_v]) continue;
        dfs(G, next_v, ptr);
    }

    last_order[v] = ptr++;
}

int main() {
    int N; cin >> N;

    // グラフ入力受取
    Graph G(N);
    REP(i,N){
        int u,k; cin>>u>>k;
        REP(j,k){
            int vlist;
            cin >> vlist;
            G[u-1].push_back(vlist-1);
        }
    }

    // 頂点 0 をスタートとした探索
    seen.assign(N, false); // 全頂点を「未訪問」に初期化
    first_order.resize(N);
    last_order.resize(N);
    int ptr = 1;

    REP(i,N){
        if(seen[i]==true) continue;
        else dfs(G, i, ptr);
    }

    REP(v,N){
        cout << v+1 << " " << first_order[v] << " " << last_order[v] << endl;
    }
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#include <stack>
#include <sstream>
#include <iomanip>
#include <cmath>
#include <string>
#include <cstdio>
#include <queue>
#include <list>
using namespace std;

int n;

struct Node{
public:
  int id, d, f, flag;
  vector<int> c;
  Node(){d = 1000000007;f = flag = 0;}
};

vector<Node> v(101);

void rec(int id, int &t){
  if(v[id].flag)return;
  else          v[id].flag = 1;
  v[id].d = min(v[id].d, ++t);
  for(int i=0;i<v[id].c.size();i++) {
    rec(v[id].c[i], t);
  }
  v[id].f = max(v[id].f, ++t);
}


bool asc(const Node &right, const Node &left){return right.id < left.id;}

int main(){
  cin >> n;
  
  v[0].id = 0;  
  for(int i=1;i<=n;i++){
    int t, a;  cin >> a >> t;
    vector<int> b(t);
    for(int j=0;j<t;j++){
      int val;cin >> val;
      b[j] = val;
    }
    v[a].id = a;
    v[a].c = b;
  }
  sort(v.begin(), v.end(), asc);

  int ti = 0;
  for(int i=1;i<=n;i++){
    rec(i, ti);
  }

  for(int i=1;i<=n;i++){
    printf("%d %d %d\n", v[i].id, v[i].d, v[i].f);
  }
  return 0;
}

C++: #include <stdio.h>

int numberd=1, numberf=1;
int map[100][100];
int numofroot[100];
int visited[100];
int d[100];
int f[100];
int map_size;
 
void get_map();
void print_map();
int search(int node);
void print_result();
int main()
{
  get_map();
  //print_map();
  for(int i=0;i<map_size;i++)
    {
      if(d[i]==0)
	{
	  search(i);
	}
    } 
  print_result();
  return 0;
}

int search(int node)
{
  int k;
  if(d[node]==0)//not visited
    {
      d[node]=numberd;//visited
      numberd++;
      if(numofroot[node]!=0)
	{
	  for(int i=0;i<numofroot[node];i++)
	    {
		{
		  k=search(map[node][i]-1);
		  if(k==-1)
		    {
		      //f[node]=numberd;
		      //numberd++;
		      //return -1;
		    }
		}
	    }
	}
      //else
	{
	  f[node]=numberd;
	  numberd++;
	  return -1;
	}
    }
  else//visited
    {
      return 1;
    }

  return -1;
}

void print_result()
{
  for(int i=0;i<map_size;i++)
    {
      printf("%d %d %d\n",i+1, d[i],f[i]);
    }
  return ;
}

void get_map()
{
  int k;
   scanf("%d", &map_size);
  for(int i=0;i<map_size;i++)
    {
      scanf("%d", &k);
      scanf("%d", &numofroot[i]);
      for(int j=0;j<numofroot[i];j++)
	{
	  scanf("%d", &map[i][j]);
	}
    }
  return ;
}

void print_map()
{
  for(int i=0;i<map_size;i++)
   {
     printf("%d", numofroot[i]);
     for(int j=0;j<numofroot[i];j++)
       {
	 printf("%d", map[i][j]);
       }
     if(i!=map_size-1)
       {
     puts("");
       }
   }
  puts("");
  return ;
}

C++: #include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll MOD = 1e9 + 7;
const ll INF = 1LL << 60;
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define debug(x) cerr << #x << ": " << x << endl;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}

vector<vector<ll>> G;
vector<ll> d, f;
vector<bool> b;
ll t;

ll dfs(ll v, ll t) {
    b[v] = true;
    d[v] = t;
    for (auto nv : G[v]) {
        if (b[nv]) continue;
        t = dfs(nv, t + 1);
    }
    f[v] = t + 1;
    return t + 1;
}

int main() {
    ll n;
    cin >> n;
    G.resize(n), d.resize(n), f.resize(n), b.resize(n);
    rep(i, n) {
        ll u, k;
        cin >> u >> k;
        u--;
        rep(j, k) {
            ll v;
            cin >> v;
            v--;
            G[u].emplace_back(v);
        }
    }
    ll now = 0;
    rep(i, n) {
        if(b[i]) continue;
        now = dfs(i, now + 1);
    }
    rep(i, n) cout << i+1 << " " << d[i] << " " << f[i] << endl;
}