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

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	currentVertex := &vertices[currentId-1]
	if currentVertex.isVisited() {
		return timestamp
	}
	timestamp = timestamp + 1
	currentVertex.firstVisitAt = timestamp
	for _, adjId := range currentVertex.adjs {
		timestamp = dfs(adjId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

func solveDfs(vertices []vertex) {
	timestamp := 0
	for {
		vid := vertexId(-1)
		for i := 0; i < len(vertices); i++ {
			if !vertices[i].isVisited() {
				vid = vertexId(i+1)
				break
			}
		}
		if vid > 0 {
			timestamp = dfs(vid, timestamp, vertices)
		} else {
			break
		}
	}
}

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)
	}

	solveDfs(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 <iostream>
#include <vector>
using namespace std;
using Graph = vector<vector<int>>;

// 深さ優先探索
vector<bool> seen;
vector<int> start_ptr;
vector<int> end_ptr;
void dfs(const Graph &G, int v, int &ptr) {
    seen[v] = true;
    start_ptr[v]=ptr;
    ptr++;
    for (auto next_v : G[v]) { 
        if (seen[next_v]) continue;
        dfs(G, next_v, ptr); // 再帰的に探索
    }
    end_ptr[v]=ptr;
    ptr++;
}

int main() {
    // 頂点数と辺数
    int N; cin >> N;

    // グラフ入力受取
    Graph G(N);
    for (int i = 0; i < N; ++i) {
        int a, b;
        cin >> a >> b;
        for(int j=0;j<b;j++){
            int v; cin >>v;
        
        G[a-1].push_back(v-1);
        }
    }

    // 全頂点が訪問済みになるまで探索
    seen.assign(N, false);
    int ptr=1;
    start_ptr.resize(N);
    end_ptr.resize(N);
    for (int v = 0; v < N; ++v) {
        if (seen[v]) continue; // v が探索済みだったらスルー
        dfs(G, v, ptr); // v が未探索なら v を始点とした DFS を行う
    }
    for(int i=0;i<N;i++){
    cout << i+1 <<" "<<start_ptr[i]<<" "<<end_ptr[i]<< endl;
    }
}

C++: #include<stdio.h>
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],tt;
void dfs_visit(int u){
    int v;
    color[u]=GRAY;
    d[u]=++tt;
    for(v=0;v<n;v++){
        if(M[u][v]==0)continue;
        if(color[v]==WHITE){dfs_visit(v);}
    }
    color[u]=BLACK;
    f[u]=++tt;;
}
void dfs(){
    int u;
    for(u=0;u<n;u++)color[u]=WHITE;
    tt=0;
    for(u=0;u<n;u++){
        if(color[u]==WHITE)dfs_visit(u);
    }
    for(u=0;u<n;u++)printf("%d %d %d\n",u+1,d[u],f[u]);
}
int main(){
    int u,v,k,i,j;
    scanf("%d",&n);
    for(i=0;i<n;i++){
        for(j=0;j<n;j++)M[i][j]=0;
    }
    for(i=0;i<n;i++){
        scanf("%d %d",&u,&k);
        u--;
        for(j=0;j<k;j++){
            scanf("%d",&v);
            v--;
            M[u][v]=1;
        }
    }
    dfs();
}

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;
  for(int i=0;i<n;i++)
    if(!u[i]) dfs(i,p);
  for(int i=0;i<n;i++) cout<<i+1<<" "<<d[i]<<" "<<f[i]<<endl;;
  return 0;
}

C++: #include <iostream>
#include<string>
#include<cmath>
#include<algorithm>
#include<cctype>
#include<queue>
#include<stack>
#include<stdio.h>
#include<vector>
#include<set>
#include<map>
#include<array>
#include<iomanip>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
typedef int long long ll;
static const int N=100;
static const int white=0;
static const int gray=1;
static const int black=2;

int n,d[N],f[N],tt;
int color[N],nt[N];
int mp[N][N];

int next(int u){
    
    for(int v=nt[u];v<n;v++){
        nt[u]=v+1;
        if(mp[u][v]!=0)return v;
    }
    return -1;
}


void dfs_visit(int r){
    
    rep(i,n)nt[i]=0;
    stack<int> s;
    s.push(r);
    color[r]=gray;
    d[r]=++tt;
    while(!s.empty()){
        int u=s.top();
        int v=next(u);
        if(v!=-1){
            if(color[v]==white){
            d[v]=++tt;
            color[v]=gray;
            s.push(v);
            }
        }else{
            color[u]=black;
            f[u]=++tt;
            s.pop();
        }
    }
}



void dfs(){

    rep(i,n){color[i]=white;nt[i]=0;}
    tt=0;
    
    for(int i=0;i<n;i++){
        if(color[i]==white){
            dfs_visit(i);
        }
    }
    rep(i,n){
        cout<<i+1<<" "<<d[i]<<" "<<f[i]<<endl;
    }
    
}

int main(){
    cin>>n;
    
    for(int i=0;i<n;i++){
        for(int j=0;j<n;j++){
            mp[i][j]=0;
        }
    }
    for(int i=0;i<n;i++){
        int a,b;
        cin>>a>>b;
        rep(j,b){
            int c;
            cin>>c;
            mp[a-1][c-1]=1;
        }
    }
    
    dfs();
    
    return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#include <set>
#include <cmath>
#include <deque>
#include <iterator>
#include <map>
#include <queue>
#include <string>
#include <tuple>
#include <utility>
using namespace std;

using ll=long long;
template<class T> using V = vector<T>;
template<class T, class U> using P = pair<T, U>;
using vll = V<ll>;
using vvll = V<vll>;
#define rep(i, k, n) for (ll i=k; i<(ll)n; ++i)
#define REP(i, n) rep(i, 0, n)
template<class T> inline bool chmax(T& a, T b) {if (a<b) {a=b; return true;} return false;}
template<class T> inline bool chmin(T& a, T b) {if (a>b) {a=b; return true;} return false;}

vll d(100, -1), f(100, -1);
vvll edges(100, vll());
ll n;

ll dfs(ll i, ll t) {
  if (d.at(i) != -1) return t-1;
  d.at(i) = t;
  REP(toi, edges.at(i).size()) {
    t = dfs(edges.at(i).at(toi), ++t);
  }
  return f.at(i) = t+1;
}

int main() {
  cin >> n;
  REP(i, n) {
    ll u, k; cin >> u >> k;
    REP(j, k) {
      ll to; cin >> to;
      edges.at(u-1).push_back(to-1);
    }
  }
  ll t = 0;
  REP(i, n) {
    t = dfs(i, t+1);
  }
  REP(i, n) {
    cout << i+1 << ' ' << d.at(i) << ' ' << f.at(i) << endl;
  }
  return 0;
}