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>
#include <queue>
#include <string>
#include <algorithm>
#include <utility>
#include <climits>
#include <cstring>
#include <cstdio>

using namespace std;
typedef long long int llg;

const int INF = 1000001000;
#define REP(var, count) for(int var=0; var<count; var++)

template <typename T>
using reverse_queue = std::priority_queue<T, std::vector<T>, std::greater<T> >;

template<typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val){
	std::fill( (T*)array, (T*)(array+N), val );
}

vector<int> rin[105];
pair<int, int> res[105];

int bfs(int a, int time) {
	res[a].first = time;
	for ( int r : rin[a] ) {
		if ( res[r].first != -1 ) { continue; }
		time = bfs(r, time + 1);
	}
	res[a].second = time + 1;
	return res[a].second;
}

int main(void) {
	int N;
	cin >> N;
	
	for(int i=1; i<=N; i++) {
		res[i].first = -1;
		res[i].second = -1;
		
		int U, K;
		cin >> U >> K;
		REP(j, K) {
			int x;
			cin >> x;
			rin[U].push_back(x);
		}
	}
	
	bfs(1, 1);
	
	for(int i=1; i<=N; i++) {
		printf("%d %d %d\n", i, res[i].first, res[i].second);
	}
}

C++: #include<bits/stdc++.h>
#define rep(i,n) for(int i = 0;i<n;i++)
using namespace std;
typedef pair<int,int> P;
typedef long long ll;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0;}
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0;}

int n; //頂点数
vector<vector<int> > g;//グラフ
vector<int>d;//到着時刻を記録
vector<int>f;//終了時刻を記録
void dfs(int v,int& i) {
    if(d[v] == 0) {
        i++;
        d[v] = i;//到着時刻を記録
    }    
    
    for(int next_v : g[v]) {
        if(d[next_v]) continue;//訪問済みなら飛ばす
        dfs(next_v,i);//隣接頂点について探索
    }
    if(f[v] == 0) {
        i++;
        f[v] = i;//終了時刻を記録
    }
}
int main() {
    cin >> n;
    //nで初期化
    g.resize(n);
    f.resize(n);
    d.resize(n);
    rep(i,n) {
        int u; //頂点番号
        cin >> u;
        u--;
        int k; //出次数
        cin >> k;
        rep(j,k) {
            int v;//隣接する頂点
            cin >> v;
            v--;
            g[u].push_back(v);
        }
    }
    int count = 0;
    //各頂点からdfs
    for(int i = 0;i<n;i++) {
        dfs(i,count);
    }    
    //各頂点について到着時刻と終了時刻を出力
    for(int i = 0;i<n;i++) {
        cout << i+1 << " " << d[i] << " " << f[i] << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <sstream>
#include <cstdio>
#include <stdlib.h>
#include <string>
#include <vector>
#include<stack>
#include <algorithm>
using namespace std;
#define max 101
#define WHITE 0
#define BLACK 1
#define GRAY -1
int color[max],d[max],f[max];
int t,varry[max][max];
stack<int> s;
int next(int u){
  int nv=-1;
  for(int i=0;i<varry[u][0];i++){
    if(color[varry[u][i+1]]==WHITE){
      nv=varry[u][i+1];
      break;
    }
  }
  
  return nv;
}
void visit(int r){
  int u,v;
  s.push(r);
  color[r]=GRAY;
  d[r]=++t;
  while(!s.empty()){
    u=s.top();
    v=next(u);
    if(v!=-1){
      if(color[v]==WHITE){
	s.push(v);
	color[v]=GRAY;
	d[v]=++t;
      }
    }
    else{
      s.pop();
      color[u]=BLACK;
      f[u]=++t;
      
    }
  }
}
void dfs(int u){
  for(int i=1;i<=u;i++)
    if(color[i]==WHITE)visit(i);
}
int main(){
  int n,u;
  cin>>n;
  for(int k=0;k<n;k++){
    cin>>u;
    cin>>varry[u][0];
    for(int i=0;i<varry[u][0];i++)
      cin>>varry[u][i+1];

  }
  dfs(n);
  for(int i=1;i<=n;i++){
    cout<<i<<" "<<d[i]<<" "<<f[i]<<endl;
  }


  return 0;
}

C++: #include <algorithm>
#include<iostream>
#include<vector>
#include<deque>
#include<queue>
#include<list>
#include<stack>
#include<map>
#include<set>
#include<string>
#include <sstream>
#include<bitset>

#include<stdlib.h>
#include<string.h>
#include<math.h>
#include<limits.h>

using namespace std;
const int INF = 0x7fffffff;

int gcd(int x,int y){
  int mi,ma;
  ma = max(x,y);
  mi = min(x,y);
  if(ma % mi == 0){
    return mi;
  }
  else{
    return gcd(mi,ma % mi);
  }
}

using Graph = vector<vector<int>>;

int g[101][101];
int seen[101];
int stamp[2][101];
int n;
int t;

void dfs(int v){
  seen[v] = 1;
  int ii;

  //cout << v << endl;
  
  stamp[0][v] = t;
  t++;

  //for(ii=1;ii<=n;ii++){
  //  cout << seen[ii] << endl;
  //}
  
  for(ii=1;ii<=n;ii++){
    //cout << "v:"<< v << "ii:" << ii << " " << g[v][ii] << endl;

    if(seen[ii] == 1){continue;}
    //cout << "v:"<< v << "ii:" << ii << " " << g[v][ii] << endl;

    if(g[v][ii] == 1){
      dfs(ii);
    }
  }
  
  stamp[1][v] = t;
  t++;
}

int main(){
  long ii,jj,kk;
  vector<int> a;


  memset(g,0,sizeof(g));

  memset(stamp,0,sizeof(stamp));
  
  cin >> n;

  int v,vn,r;
  
  for(ii=0;ii<n;ii++){
    cin >> v;
    cin >> vn;
    for(jj=0;jj<vn;jj++){
      cin >> r;
      g[v][r] = 1;
    }
  }

  //for(ii=1;ii<=n;ii++){
  //  for(jj=1;jj<=n;jj++){
  //    cout << g[ii][jj] ;
  //    if(jj!=n){
  //      cout << " ";
  //    }
  //  }
  //  cout << endl;
  //}  
  
  t = 1;
  memset(seen,0,sizeof(seen));

  for(ii=1;ii<=n;ii++){
    if(seen[ii] == 0){
      dfs(ii);
    }

  }


  for(ii=1;ii<=n;ii++){
    cout << ii << " " << stamp[0][ii] << " " << stamp[1][ii] << endl;
  }
  return 0;
}