Go: package main

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

type TimeRecord struct {
	discoverTime int
	finishTime   int
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	timeRecordMap := make([]TimeRecord, n)
	childrenMap := make([][]int, n)
	for i := 1; i <= n; i++ {
		node, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		timeRecordMap[node-1] = TimeRecord{-1, -1}

		childNum, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		childrenMap[node-1] = make([]int, childNum)
		for j := 0; j < childNum; j++ {
			child, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			childrenMap[node-1][j] = child
		}
	}

	// TODO: always start with 1?
	timer := 1
	visit(1, &timer, childrenMap, timeRecordMap)
	for k, v := range timeRecordMap {
		fmt.Printf("%d %d %d\n", k+1, v.discoverTime, v.finishTime)
	}
}

func visit(currentNode int, timer *int, childrenMap [][]int, timeRecordMap []TimeRecord) {
	if timeRecordMap[currentNode-1].discoverTime > 0 {
		return
	}
	children := childrenMap[currentNode-1]
	timeRecordMap[currentNode-1] = TimeRecord{*timer, timeRecordMap[currentNode-1].finishTime}
	(*timer)++
	for i := 0; i < len(children); i++ {
		visit(children[i], timer, childrenMap, timeRecordMap)
	}
	timeRecordMap[currentNode-1] = TimeRecord{timeRecordMap[currentNode-1].discoverTime, *timer}
	(*timer)++
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

C++: #include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <ctime>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>

#define rep(i,n)   for (int i = 0; i < (n); ++i)
#define sort(a)    sort((a).begin(), (a).end());
#define uniq(a)    SORT(a);(a).erase(unique((a).begin(), (a).end()), (a).end());
#define find(a,x)  find((a).begin(), (a).end(), (x)) != (a).end()
#define reverse(a) reverse((a).begin(), (a).end());
#define out(d) cout << (d);
#define outl(d) std::cout<<(d)<<"\n";
#define Yes() printf("Yes\n");
#define No() printf("No\n");
#define YES() printf("YES\n");
#define NO() printf("NO\n");
#define ceil(x, y) ((x + y - 1) / (y))

using namespace std;
using ll = long long;
using P = pair<ll,ll>;

const ll MOD = 1000000007; // 10^9 + 7

const int MAX_N = 100;
int s[MAX_N + 1], e[MAX_N + 1];
int N, t = 1;
vector<vector<int>> g(MAX_N + 1);

void dfs(int i) {
  if (s[i] > 0) return;
  // cout << "i = " << i << ", t = " << t << endl;

  s[i] = t++;
  for (int j = 0; j < g[i].size(); j++) {
    dfs(g[i][j]);
  }
  e[i] = t++;
}

void dfs() {
  for (int i = 1; i <= N; i++) {
    if (s[i] > 0) continue;
    dfs(i);
  }
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  srand((unsigned)time(NULL));

  cin >> N;
  for (int i = 0; i < N; i++) {
    int u; cin >> u;
    int k; cin >> k;
    for (int ki = 0; ki < k; ki++) {
      int tmp; cin >> tmp;
      g[u].push_back(tmp);
    }
    sort(g[u])
  }

  memset(s, 0, sizeof(s));
  memset(e, 0, sizeof(e));

  // outl("-------------")
  // for (int i = 1; i <= N; i++) {
  //   cout << i << " ";
  //   for (int j = 0; j < g[i].size(); j++) {
  //     cout << g[i][j] << " ";
  //   }
  //   cout << endl;
  // }
  // outl("-------------")

  dfs();

  for (int i = 1; i <= N; i++) {
    cout << i << " " << s[i] << " " << e[i] << endl;
  }
}

C++: #include <map>
#include <set>
#include <list>
#include <cmath>
#include <deque>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <complex>
#include <cstdlib>
#include <cstring>
#include <numeric>
#include <utility>
#include <iostream>
#include <algorithm>
#include <functional>
#include <unordered_map>
#include <unordered_set>

using namespace std;

#define ll long long
#define ull unsigned long long
#define INF (1 << 30)
#define LLINF (1LL << 62)
#define MOD7 1000000007
#define MOD9 1000000009
#define eps 1e-9
#define P pair<int, int>
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pul pair<ull, ull>
#define all(a) (a).begin(), (a).end()
#define FOR(i,a,b) for (int i=(a);i<(b);++i)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);--i)
#define REP(i,n) for (int i=0;i<(n);++i)
#define RREP(i,n) for (int i=(n)-1;i>=0;--i)

void YES() { cout << "YES\n"; }
void NO() { cout << "NO\n"; }
void Yes() { cout << "Yes\n"; }
void No() { cout << "No\n"; }
void yes() { cout << "yes" << endl; }
void no() { cout << "no" << endl; }

template<class T>
class DirectedGraph {
public:
	class Edge {
	public:
		int to;
		T cost;

		Edge(int t, T c) : to(t), cost(c) {}
	};

	vector<vector<Edge>> G;
	vector<int> visit;
	vector<pii> stamp{ 0 };
	int V;

	DirectedGraph(int n = 0) {
		resize(n);
	}

	void resize(int n) {
		V = n;
		G.resize(n);
		visit.resize(n);
		stamp.resize(n);
	}

	void addEdge(int from, int to, T cost = 0) {
		int v = max(from, to);
		if (v >= V)
			resize(v + 1);
		G[from].push_back(Edge(to, cost));
	}

	int t = 1;
	void dfs(int s) {
		if (stamp[s].first == 0)
			stamp[s].first = t++;
		else
			return;

		for (int i = 0; i < G[s].size(); ++i) {
			dfs(G[s][i].to);
		}
		stamp[s].second = t++;
	}

	int bfs() {

	}
};

int main() {
	DirectedGraph<int> g;
	int n, id, k, to;
	cin >> n;
	for (int i = 0; i < n; ++i) {
		cin >> id >> k;
		while (k--) {
			cin >> to;
			g.addEdge(id, to);
		}
	}

	g.dfs(1);
	for (int i = 1; i <= n; ++i) {
		cout << i << " " << g.stamp[i].first << " " << g.stamp[i].second << endl;
	}

	return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;
static const int N=100;
static const int WHITE=0;
static const int GRAY=1;
static const int BLACK=2;

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

//u?????£??\??????v?????????????????????
int next(int u){
	for (int v = nt[u]; v < n; ++v) {
		nt[u]=v+1;
		if(M[u][v])return v;
	}
	return -1;
}

//?????????????????¨????????±???????????¢?´¢
void dfs_visit(int r){
	for (int i = 0; i < n; ++i) {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){
				color[v]=GRAY;
				d[v]=++tt;
				S.push(v);
			}
		}else{
			S.pop();
			color[u]=BLACK;
			f[u]=++tt;
		}
	}
}

void dfs(){
	//?????????
	for (int i = 0; i < n; ++i) {
		color[i]=WHITE;
		nt[i]=0;
	}
	tt=0;
	//????¨???????u????§??????¨????????±???????????¢?´¢
	for (int u = 0; u < n; ++u) {
		if(color[u]==WHITE)dfs_visit(u);
	}
	for (int i = 0; i < n; ++i) {
		cout<<i+1<<" "<<d[i]<<" "<<f[i]<<endl;
	}
}


int main(){
	int u,k,v;
	cin>>n;
	for (int i = 0; i < n; ++i) {
		for (int j = 0; j < n; ++j) {
			M[i][j]=0;
		}
	}
	for (int i = 0; i < n; ++i) {
		cin>>u>>k;
		u--;
		for (int j = 0; j < k; ++j) {
			cin>>v;
			v--;
			M[u][v]=1;
		}
	}
	dfs();
	return 0;
}

C++: #include<iostream>
#include<cstdio>
#define WHITE 0
#define GRAY 1
#define BLACK 2
#define N 100
using namespace std;
int M[N][N],n;
int color[N],d[N],f[N],tt;
void dfs_visit(int u)
{
  int v;
  color [u] = GRAY ;
  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(i = 0;j<k;j++)
      {
        scanf("%d",&v);
        v--;
        M[u][v] =1;
      }
  }
  dfs();
  return  0 ;
}