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 <algorithm>
#include <bitset>
#include <cctype>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
using namespace std;

void dfs(const vector<vector<int>>& edges, vector<int>& ds, vector<int>& fs, int u, int& t) {
    if (ds[u] > 0) {
        return;
    }
    ds[u] = ++t;
    for (auto v : edges[u]) {
        dfs(edges, ds, fs, v, t);
    }
    fs[u] = ++t;
}

int main() {
    int n;
    cin >> n;
    vector<vector<int>> edges(n);
    for (int i = 0; i < n; i++) {
        int u, k;
        cin >> u >> k;
        u--;
        for (int j = 0; j < k; j++) {
            int v;
            cin >> v;
            v--;
            edges[u].push_back(v);
        }
        sort(begin(edges[u]), end(edges[u]));
    }
    vector<int> ds(n, -1);
    vector<int> fs(n, -1);
    int t = 0;
    dfs(edges, ds, fs, 0, t);
    for (int i = 0; i < n; i++) {
        cout << i + 1 << " " << ds[i] << " " << fs[i] << endl;
    }
}

C++: #include <iostream>
#include <string>
#include <stdio.h>
#include <stack>
using namespace std;

int d[100];
int f[100];
int map[100][100];
int tim;
int n;
stack<int> s;
void visit(int);

int main(){
	tim=0;
	int i,j,k,u,v;
	for(i=0;i<100;i++) d[i]=-1; //?????¢??\
	for(i=0;i<100;i++) f[i]=-1;
	cin >> n;
	for(i=0;i<n;i++){
		for(j=0;j<n;j++){
			map[i][j]=-1;
		}
	}
	for(i=0;i<n;i++){
		cin>>u>>k;
		for(j=0;j<k;j++){
			cin>>v;
			map[u-1][v-1]=1; //?????????????????????????????????????????????
		}
	}
	 //????????¢?????¢?´¢
	for(i=0;i<n;i++){
		if(d[i]==-1) visit(i);
	}
	for(i=0;i<n;i++) cout<< i+1 <<" "<<d[i]<<" "<<f[i]<<endl;
	return 0;
}

void visit(int a){
	s.push(a); //?????¨??°
	if(d[a]==-1){
		d[a]=++tim;
	}
	for(int i=0;i<n;i++){
		if(map[a][i]==1 && d[i]==-1){ //?????¢?´¢
			visit(i);
		}
	}
	s.pop();
	f[a]=++tim;
}

C++: #include <iostream>
#define NODE_SIZE 101

using namespace std;

struct tStamp
{
    int dsc;    //discovery
    int fin;    //finish
};

void dfs(int node, int adj[][NODE_SIZE], tStamp s[], int *cnt, int n){
    s[node].dsc = *cnt;   *cnt += 1;
    for(int i = 1; i <= n; i++){
        if(adj[node][i] && s[i].dsc == 0){
            dfs(i, adj, s, cnt, n);
        }
    }
    s[node].fin = *cnt;   *cnt += 1;
}

int main(){
    int n, u, k, v, cnt = 1;
    int adj[NODE_SIZE][NODE_SIZE] = {};
    tStamp stamp[NODE_SIZE];

    cin >> n;
    for(int i = 0; i < n; i++){
        cin >> u >> k;
        while(k--){
            cin >> v;
            adj[u][v] = 1;
        }
    }

    for(int i = 1; i <= n; i++){
        if(stamp[i].dsc == 0){
            dfs(i, adj, stamp, &cnt, n);
        }
        cout << i << " " << stamp[i].dsc << " " << stamp[i].fin << endl;
    }

    return 0;
}

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

typedef vector<int> Adj_list;
typedef vector<Adj_list> Adj_lists;

class Timekeeper{
public:
  int found;
  int complete;

  Timekeeper(){
    found = 0;
    complete = 0;
  }
};
typedef vector<Timekeeper> Timekeepers;

void dfs(const int& i, const Adj_lists& adj_lists, Timekeepers& timekeepers, int& t){
  stack<int> s;
  s.push(i + 1);
  while(!s.empty()){
    // visit top of stack
    int visit = s.top();

    // if this node is not found in past, save the time.
    if(!timekeepers[visit-1].found){
      timekeepers[visit-1].found = ++t;
    }

    // find next adjecent which is not visited yet
    for(const int& adj_list : adj_lists[visit-1]){
      if(!timekeepers[adj_list-1].found){
        s.push(adj_list);
        break;
      }
    }

    // if no adj found, delete this node
    if(visit == s.top()){
      timekeepers[visit-1].complete = ++t;
      s.pop();
    }
  }
}

int main(){

  int n;
  scanf("%d", &n);

  Adj_lists adj_lists(n);
  for(int i=0; i<n; i++){
    int u, k;
    scanf("%d %d", &u, &k);
    Adj_list adj_list(k);
    for(int j=0; j<k; j++){
      int v;
      scanf("%d", &v);
      adj_list[j] = v;
    }
    sort(adj_list.begin(), adj_list.end());
    adj_lists[u-1] = adj_list;
  }

  Timekeepers timekeepers(n);
  int t = 0;
  for(int i = 0; i < n; i++){
    if(!timekeepers[i].found) dfs(i, adj_lists, timekeepers, t);
  }

  for(int i = 0; i < timekeepers.size(); i++){
    printf("%d %d %d\n", i+1, timekeepers[i].found, timekeepers[i].complete);
  }

  return 0;
}

C++: #include <iostream>
#include <vector>
using namespace std;

int N;
int D[110];
int G[110][110];
int F[110];
int t = 1;
void dfs(int cur){
	D[cur] = t;
	t++;
	for(int i=0;i<N;i++){
		if(G[cur][i] && D[i]==0){
			dfs(i);
		}
	}
	F[cur] = t;
	t++;
}


int main(){
	while(cin >> N && N>0){
		vector<vector<int> > g(110,vector<int>(110,0));
		int u,k;
		for(int i=0;i<N;i++){
			cin >> u >> k;
			for(int j=0;j<k;j++){
				int a;
				cin >> a;
				g[u-1].push_back(a); 
			}
		}
		for(int i=0;i<N;i++){
			for(int j=0;j<g[i].size();j++){
				int f = g[i][j];
				G[i][f-1] = 1;
			}
		}
		dfs(0);
		for(int i=0;i<N;i++){
			if(D[i]==0){
				dfs(i);
			}
		}
		for(int i=0;i<N;i++){
			cout << i+1 << " " << D[i]  << " " << F[i] << endl;
		}
	}
}