Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Scan()
	num, _ := strconv.Atoi(sc.Text())
	nodes := make(map[int]*node)

	for i := 0; i < num; i++ {
		sc.Scan()
		id, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		nodeNum, _ := strconv.Atoi(sc.Text())
		n := node{id, make([]int, 0), 0, 0}
		for j := 0; j < nodeNum; j++ {
			sc.Scan()
			nid, _ := strconv.Atoi(sc.Text())
			n.nexts = append(n.nexts, nid)
		}
		nodes[id] = &n
	}

	s := Stack{}
	for i := 1; i < len(nodes)+1; i++ {
		if nodes[i].s != 0 {
			continue
		}
		walk(i, &nodes, s)
	}
	for i := 1; i < len(nodes)+1; i++ {
		fmt.Printf("%v %v %v\n", (*nodes[i]).id, (*nodes[i]).s, (*nodes[i]).e)
	}
}

var time int

func walk(nid int, nodes *map[int]*node, s Stack) {
	n := (*nodes)[nid]
	if n.s != 0 {
		return
	}
	time++
	n.s = time
	s.Push(n)
	for _, v := range n.nexts {
		walk(v, nodes, s)
	}
	time++
	n.e = time
}

type node struct {
	id    int
	nexts []int
	s     int
	e     int
}

// Stack is Stack
type Stack struct {
	stack []interface{}
}

// Push new value
func (stack *Stack) Push(val interface{}) {
	stack.stack = append(stack.stack, val)
}

// Pop new value
func (stack *Stack) Pop() interface{} {
	val := stack.stack[len(stack.stack)-1]
	stack.stack = stack.stack[0 : len(stack.stack)-1]
	return val
}

C++: #include <bits/stdc++.h>
using namespace std;
vector<int> d;
vector<int> f;
vector<bool> used;
vector< vector<int> > v;
int n;
int cnt = 1;

void dfs(int pos){
  d[pos] = cnt; cnt++;
  used[pos] = true;
  for(int i = 0; i < n; i++){
    if(v[pos][i] && !used[i]){
      dfs(i);
    }
  }
  f[pos] = cnt; cnt++;
}

int main(void){
  ios::sync_with_stdio(false);
  cin.tie(0);

  cin >> n;
  d = f = vector<int>(n, -1);
  used = vector<bool>(n, false);
  v = vector< vector<int> >(n, vector<int>(n, 0));
  for(int i = 0; i < n; i++){
    int u, k; cin >> u >> k;
    u--;
    for(int j = 0; j < k; j++){
      int a; cin >> a;
      a--;
      v[u][a] = 1;
    }
  }
  dfs(0);
  for(int i = 0; i < n; i++){
    cout << i+1 << " " << d[i] << " " << f[i] << endl;
  }

  return 0;
}

C++: #include<bits/stdc++.h>

#define rep(i,N) for(int i=0;i<N;i++)
#define rep2(i,N) for(int i=1;i<=N;i++)
using namespace std;
long long  INF=1e18;
long long mod=1e9+7;
vector<vector<int>>edge(110);
int find_time[110]={};
int end_time[110];
bool reached[110]={};
int now_time=0;

void search(int now,int before){
    if(reached[now]){
        //cout<<now+1<<"already finished"<<endl;
        return;
    }
    reached[now]=true;

    //if(now==before)return;
    now_time++;
    //cout<<now_time<<"time "<<now+1<<"p "<<before+1<<"before"<<endl;
    if(find_time[now]==0){
        find_time[now]=now_time;
    }
    
    for(auto next:edge[now]){
        if(next==before||end_time[now]!=0)continue;
        search(next,now);
    }
    now_time++;
    end_time[now]=now_time;
    return;
}
int main(){


    int n;
    cin>>n;
    rep(i,n){
        int u,k;
        cin>>u>>k;
        u--;
        rep(l,k){
            int next;
            cin>>next;
            next--;
            edge[u].emplace_back(next);
        }
    }
    rep(i,n)search(i,-1);
    //cout<<endl;
    rep(i,n){
        cout<<i+1<<" "<<find_time[i]<<" "<<end_time[i]<<endl;;
        //if(i!=n-1)cout<<endl;
    }
    return 0;

}
/*


*/

C++: #include<bits/stdc++.h>
using namespace std;
int a[105][105];
pair<int,int> ans[105];
int co;
int n;
void dfs(int x){
  if(ans[x].first==0){
    co++;
    ans[x].first = co ;
  }
  //cout << n << endl;
  for(int i=0;i<n;i++){
    //cout << a[x][i]<<endl;
    if(a[x][i]==1)dfs(i);
  }
  if(ans[x].second==0){
    co++;
    ans[x].second=co;
  }
}

int main(){
  cin >> n;
  for(int i=0;i<n;i++){
    int u,m;
    cin >> u >> m;
    for(int j=0;j<m;j++){
      int v;
      cin >> v;
      a[u-1][v-1]=1;
    }
  }
  dfs(0);
  for(int i=0;i<n;i++){
    cout << i+1 << " " << ans[i].first << " "<< ans[i].second << endl;
  }
  return 0;
}

C++: #include <iostream>
#include <vector>
#include <numeric>

const int MAXINT = std::numeric_limits<int>::max();

// typedef std::vector<std::vector<int> > mat_int;
// typedef std::vector<std::vector<bool> > mat_bool;

void dfs(std::vector<std::vector<int> >& adj_list, std::vector<int>& d, std::vector<int>& f, int& time, int root = 0 ){
  if(d[root] > time){
    d[root] = time;
    for(int const& v: adj_list[root]){
      time++;
      dfs(adj_list, d, f, time, v);
    }
    time++;
    f[root] = time;
  }

}


int main(int argc, char const *argv[]) {
  int n; // .. 100
  std::cin >> n;
  // mat_bool adj(n, std::vector<bool>(n));
  // mat_int d(n, std::vector<int>(n)), f(n, std::vector<int>(n));
  std::vector<std::vector<int> > adj_list(n);
  std::vector<int> d(n, MAXINT), f(n, MAXINT);

  for(int q=0; q<n; ++q){
    int i_plus_1, k;
    std::cin >> i_plus_1;
    std::cin >> k;
    for(int p=0; p<k; ++p){
      int j_plus_1;
      std::cin >> j_plus_1;
      // adj[i_plus_1-1][j_plus_1-1] = true;
      adj_list[i_plus_1 - 1].push_back(j_plus_1-1);
    }
  }

  int t = 1;
  dfs(adj_list, d, f, t);

  for(int i=0; i<n; ++i){
    std::cout << (i+1)
      << " " << d[i]
      << " " << f[i]
      << std::endl;

  }


  // for(auto it = adj_list.begin(); it != adj_list.end(); ++it){
  //   std::cout << ": ";
  //   for(auto jt = (*it).begin(); jt != (*it).end(); ++jt){
  //     std::cout << (*jt) << ' ';
  //   }
  //   std::cout << std::endl;
  // }

  return 0;
}

C++: #include <algorithm>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>

#define pb push_back
#define debug(x) cout<< #x <<": "<<x<<endl
#define debug2(x,y) cout<< #x <<": "<< x <<", "<< #y <<": "<< y <<endl

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<i_i, int> p_i;
typedef vector<int> vi;
typedef vector<vector<int> > vvi;
template<class T> using vv=vector<vector< T > >;

vi ts_d;
vi ts_f;

template<class T>
void dfs(int cur, int &time_visit, T graph) {
  // visiting cur
  time_visit += 1;
  ts_d[cur] = time_visit;
  for (auto dst : graph[cur]) {
    if (ts_d[dst] == 0) {
      dfs(dst, time_visit, graph);
    }
  }
  time_visit += 1;
  ts_f[cur] = time_visit;
}

int main() {
  int time = 0;
  int n;
  cin >> n;
  ts_d.reserve(n);
  ts_f.reserve(n);
  ts_d.assign(1, 0);
  vector<set<int> > graph(n, set<int>());

  for (int i = 0; i < n; ++i) {
    int num;
    cin >> num;
    num -= 1;
    int out;
    cin >> out;
    for (int j = 0; j < out; ++j) {
      int tmp;
      cin >> tmp;
      tmp -= 1;
      graph[i].insert(tmp);
    }
  }

  dfs(0, time, graph);

  for (int i = 0; i < n; ++i) {
    printf("%d %d %d\n", i+1, ts_d[i], ts_f[i]);
  }

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i, a) for(int i=0; i<(int)(a); i++)
vector<vector<int>> a;
vector<int> b;
vector<int> s;
vector<int> t;
int c = 1;

void dfs(int x)
{
  if (b[x]==1) return;
  b[x] = 1;
  s[x] = c; c++;
  for (auto v:a[x]) {
    dfs(v);
  }
  t[x] = c; c++;
}

int main()
{
  int n; cin>>n;
  a.resize(n);
  b.resize(n); rep(i, n) b[i]=0;
  s.resize(n); rep(i, n) s[i]=0;
  t.resize(n); rep(i, n) t[i]=0;
  rep(i, n) {
    int u; cin>>u; u--;
    int k; cin>>k;
    rep(j, k) {
      int v; cin>>v; v--;
      a[u].push_back(v);
    }
  }
  rep(i, n) dfs(i);
  rep(i, n) printf("%d %d %d\n", i+1, s[i], t[i]);

  return 0;
}