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;

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<int, int> Pi;
typedef vector<ll> Vec;
typedef vector<int> Vi;
typedef vector<string> Vs;
typedef vector<P> VP;
typedef vector<vector<ll>> VV;
typedef vector<vector<int>> VVi;

#define REP(i, a, b) for(ll i=(a); i<(b); i++)
#define PER(i, a, b) for(ll i=(a); i>=(b); i--)
#define rep(i, n) REP(i, 0, n)
#define per(i, n) PER(i, n, 0)
const ll INF=1e18+18;
const ll MAX=100005;
const ll MOD=1000000007;
#define Yes(n) cout << ((n) ? "Yes" : "No") << endl;
#define YES(n) cout << ((n) ? "YES" : "NO") << endl;
#define ALL(v) v.begin(), v.end()
#define rALL(v) v.rbegin(), v.rend()
#define pb(x) push_back(x)
#define mp(a, b) make_pair(a,b)
#define Each(a,b) for(auto &a :b)
#define REPM(i, mp) for (auto i = mp.begin(); i != mp.end(); ++i)
#define dbg(x_) cerr << #x_ << ":" << x_ << endl;
#define dbgmap(mp) cerr << #mp << ":"<<endl; for (auto i = mp.begin(); i != mp.end(); ++i) { cerr << i->first <<":"<<i->second << endl;}
#define dbgarr(n,m,arr) rep(i,n){rep(j,m){cerr<<arr[i][j]<<" ";}cerr<<endl;}
#define dbgdp(n,arr) rep(i,n){cerr<<arr[i]<<" ";}cerr<<endl;
#define dbgmint(n,arr) rep(i,n){cerr<<arr[i].x<<" ";}cerr<<endl;
#define out(a) cout<<a<<endl
#define out2(a,b) cout<<a<<" "<<b<<endl
#define vout(v) rep(i,v.size()){cout<<v[i]<<" ";}cout<<endl
#define Uniq(v) v.erase(unique(v.begin(), v.end()), v.end())
#define fi first
#define se second

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return true; } return false; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return true; } return false; }

template<typename T1, typename T2>
ostream &operator<<(ostream &s, const pair<T1, T2> &p) { return s<<"("<<p.first<<", "<<p.second<<")"; }

template<typename T>istream& operator>>(istream&i,vector<T>&v)
{rep(j,v.size())i>>v[j];return i;}

// vector
template<typename T>
ostream &operator<<(ostream &s, const vector<T> &v) {
    int len=v.size();
    for(int i=0; i<len; ++i) {
        s<<v[i];
        if(i<len-1) s<<"	";
    }
    return s;
}

// 2 dimentional vector
template<typename T>
ostream &operator<<(ostream &s, const vector<vector<T> > &vv) {
    int len=vv.size();
    for(int i=0; i<len; ++i) {
        s<<vv[i]<<endl;
    }
    return s;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout<<std::setprecision(10);

    ll n;
    cin>>n;
    VV g(n);
    rep(i,n){
        ll u,k;
        cin>>u>>k;
        u--;
        rep(j,k){
            ll x;
            cin>>x;
            x--;
            g[u].pb(x);
        }
    }

    Vec d(n,-1);
    Vec f(n,-1);
    ll time = 0;
    auto dfs = [&](auto dfs,ll v)->void{
        Each(x,g[v]){
            if(d[x]==-1){
                time++;
                d[x] = time;
                dfs(dfs,x);
            }
        }
        if(f[v]==-1){
            time++;
            f[v] = time;
        }
    };
    rep(i,n){
        if(d[i]==-1){
            time++;
            d[i] = time;
        }
        dfs(dfs,i);
    }
    rep(i,n){
        cout<<i+1<<" "<<d[i]<<" "<<f[i]<<endl;
    }
    return  0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define int long long
vector<vector<int> > G;
int d[111],f[111],u[111];
void dfs(int v,int& p){
  if(u[v]) return;
  u[v]=1;
  sort(G[v].begin(),G[v].end());
  d[v]=++p;
  for(int u:G[v]) dfs(u,p);
  f[v]=++p;
}
signed main(){
  int n;
  cin>>n;
  G.resize(n,vector<int>());
  for(int i=0;i<n;i++){
    int u,k;
    cin>>u>>k;
    u--;
    for(int j=0;j<k;j++){
      int c;
      cin>>c;
      c--;
      G[u].push_back(c);
    }
  }
  int p=0;
  dfs(0,p);
  for(int i=0;i<n;i++) cout<<i+1<<" "<<d[i]<<" "<<f[i]<<endl;;
  return 0;
}

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

#define ul unsigned long long
#define ll long long

ll g[101][101],a[101][2],ct;

void dfs(ll ci) {
  //cout<<ci<<endl;
  if (a[ci][0]) return;
  ll ni;
  ct++;
  a[ci][0]=ct;

  for (ll i = 1; i <= g[ci][0]; i++)
  {
    ni=g[ci][i];
    if (ni>0) {
      g[ci][i] = 0;
        dfs(ni);
    }
  }

  ct++;
  a[ci][1] = ct;
}

int main()
{
  ll n,ci;
  cin>>n;
  fill_n(a[0],101*2,0);
  a[0][0]=1;
  ct=0;

  for (ll i = 0; i < n; i++)
  {
    cin>>ci;
    cin>>g[ci][0];
    for (ll j = 1; j <= g[ci][0]; j++)
    {
      cin>>g[ci][j];
    }
  }

  for (ll i = 1; i <= n; i++)
  {
    dfs(i);
  }
  

  for (ll i = 1; i <= n; i++)
  {
    cout<< (i) <<" "<<a[i][0]<<" "<<a[i][1]<<endl;
  }
  

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define _GLIBCXX_DEBUG

vector<int> d;
vector<int> f;
int t;

void dfs(int p, vector<vector<int>> dst) {
  d[p] = t;
  for (int x : dst[p]) {
    if (!d[x]) {
      ++t;
      dfs(x, dst);
    }
  }
  f[p] = ++t;
}

int main() {
  int n;
  cin >> n;
  // bug
  vector<vector<int>> dst;
  dst = vector<vector<int>>(n + 1);
  d = vector<int>(n + 1, 0);
  f = vector<int>(n + 1, 0);
  for (int i = 1; i <= n; i++) {
    int u, k;
    cin >> u >> k;
    for (int j = 0; j < k; j++) {
      int v;
      cin >> v;
      dst[u].push_back(v);
    }
  }
  t = 0;
  // bug:未発見の頂点が残る場合を考えていなかった。
  // dfs(1, 1);
  for (int i = 1; i <= n; i++) {
    if (!d[i]) {
      ++t;
      dfs(i, dst);
    }
  }
  for (int i = 1; i <= n; i++) {
    cout << i << ' ' << d[i] << ' ' << f[i] << endl;
  }
}