Go: package main

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

/***************************************************************
stackによる深さ優先探索を実装する。
***************************************************************/

const (
	N     = 100
	WHITE = 0
	GRAY  = 1
	BLACK = 2
)

var (
	n            int
	Adj          [N][N]int
	statusColor  [N]int
	discoverTime [N]int
	finishTime   [N]int
	clock        int
	nt           [N]int
)

/***************************************************************
Stackの定義:
- field
	container: ノードの格納されたスライス
	sp: スタックポインタ
- method
	size(): スタックに積まれているノードの個数を返す
	top(): スタックの一番上に積まれているノードを返す
	isEmpty(): スタックが空かどうかを返す
	pop(): スタックの要素をポップし削除する
	push(): スタックに要素を積む
***************************************************************/

type Stack struct {
	container []int
	sp        int
}

func (s *Stack) size() int {
	return len(s.container)
}

func (s *Stack) top() int {
	return s.container[s.sp]
}

func (s *Stack) isEmpty() bool {
	return s.sp == 0
}

func (s *Stack) pop() int {
	_pop := func() {
		s.container = s.container[:len(s.container)-1]
	}
	defer _pop()
	if s.isEmpty() {
		panic("There is no elements in stack!")
	}
	s.sp--
	return s.container[s.sp]
}

func (s *Stack) push(n int) {
	s.sp++
	s.container[s.sp] = n
}

func next(u int) int {
	for v := nt[u]; v < n; v++ {
		nt[u] = v + 1
		if Adj[u][v] == 1 {
			return v
		}
	}
	return -1
}

func _DFS(target int) {
	for i := 0; i < n; i++ {
		nt[i] = 0
	}
	stack := new(Stack)
	stack.container = make([]int, N+1)
	stack.push(target)
	statusColor[target] = GRAY
	clock++
	discoverTime[target] = clock
	for !stack.isEmpty() {
		u := stack.top()
		v := next(u)
		if v != -1 {
			if statusColor[v] == WHITE {
				statusColor[v] = GRAY
				clock++
				discoverTime[v] = clock
				stack.push(v)
			}
		} else {
			stack.pop()
			statusColor[u] = BLACK
			clock++
			finishTime[u] = clock
		}
	}
}

func DFS() {
	for i := 0; i < n; i++ {
		statusColor[i] = WHITE
		nt[i] = 0
	}
	clock = 0
	for i := 0; i < n; i++ {
		if statusColor[i] == WHITE {
			_DFS(i)
		}
	}
	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", i+1, discoverTime[i], finishTime[i])
	}
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	scanner.Scan()
	n, _ = strconv.Atoi(scanner.Text())
	for i := 0; i < n; i++ {
		for j := 0; j < n; j++ {
			Adj[i][j] = 0
		}
	}
	for i := 0; i < n; i++ {
		scanner.Scan()
		u, _ := strconv.Atoi(scanner.Text())
		scanner.Scan()
		k, _ := strconv.Atoi(scanner.Text())
		u--
		for j := 0; j < k; j++ {
			scanner.Scan()
			v, _ := strconv.Atoi(scanner.Text())
			v--
			Adj[u][v] = 1
		}
	}

	DFS()
}

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

using namespace std;
#define fordebug int hoge;cin>>hoge;
#define DEKAI 1000000007
#define INF (1<<28)
#define lp(i,n) for(int i=0;i<n;i++)
#define lps(i,j,n) for(int i=j;i<n;i++)
#define floot10 cout<<fixed<<setprecision(10);
#define int long long
vector<int> v[200];
int n,t=1;
int d[200],f[200],done[200];

void dfs(int now){
	//cout<<now<<endl;
	d[now]=t;
	t++;
	done[now]=1;
	lp(i,v[now].size()){
		if(done[v[now][i]]==1) continue;
		dfs(v[now][i]);
	}
	f[now]=t;
	t++;
}

signed main(){
	cin>>n;
	lp(z,n){
		int i,c;
		cin>>i>>c;
		lp(j,c){
			int hoge;
			cin>>hoge;
			v[i].push_back(hoge);
		}
	}
	lps(i,1,n+1){
		if(done[i]==0)
			dfs(i);
	}
	lps(i,1,1+n){
		cout<<i<<" "<<d[i]<<" "<<f[i]<<endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
 
#define rep(i,n) for(ll i=0;i<n;++i)
#define ALL(a) (a).begin(),(a).end()
 
using namespace std;
using ll  = long long;
using pll = pair<ll, ll>;
using pdd = pair<double, double>;
 
const ll MOD  = 1e9+7;
const ll LINF = 1LL << 60;
const int INF = 1e9 + 7;

int n;
vector<vector<int>> g(100);

int d[100], f[100];
bool used[100] = {};
int t = 0;

void dfs(int pos){
    d[pos] = ++t;
    used[pos] = true;

    rep(i, g[pos].size()){
        if(used[g[pos][i]])continue;
        dfs(g[pos][i]);
    }

    f[pos] = ++t;
}

int main(){
    cin >> n;

    rep(i, n){
        int u, k;
        cin >> u >> k;
        rep(j, k){
            int v;
            cin >> v;
            v--;
            g[i].push_back(v);
        }
    }

    rep(i, n){
        if(!used[i])dfs(i);
        cout << i+1 << " " << d[i] << " " << f[i] << endl;
    }
}

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

int main(){
  vector<int> G[100];
  stack<int> q;
  vector<int> d(100,200000000),f(100,200000000);
  int n,u,k,v,time=0;
  bool flg;
  
  cin >> n;
  //G.push_back(new vector<int>(,10));
  for (int i=0;i<n;i++){
    cin >> u>> k;
    for (int j=0;j<k;j++){
      cin >> v;
      G[u-1].push_back(v-1);
    }
  }
  for (int vi=0;vi<n;vi++){
    if (d[vi]<=time)continue;
    q.push(vi);
    d[vi]=++time;
    while (!q.empty()){
      u=q.top();
      for (int i=0;i<G[u].size();i++){
	v=G[u][i];
	if (d[v]>time){
	  q.push(v);
	  d[v]=++time;
	  flg=true;
	  break;
	}
      }
      if (!flg){
	q.pop();
	f[u]=++time;
      }else{
	flg=false;
      }
    }
    
  }
  for (int i=0;i<n;i++)
    cout << i+1 <<" "<< d[i]<<" "<<f[i]<<endl;
  
  return 0;
}

C++: #include<iostream>
#include<string>
#include<vector>
#include<cstdio>
#include<sstream>
#include<algorithm>
#include<cmath>
#include<map>
using namespace std;
int G[101][101];
bool used[101];
int f[101],s[101];
int cnt=0;
void dfs(int now){
	cnt++;
	s[now]=cnt;
	used[now]=1;
	for(int i=1;i<=100;i++){
	if(G[now][i]&&used[i]==0)dfs(i);
	}
	cnt++;
	f[now]=cnt;
}

int main(){
int n;
cin>>n;
for(int i=0;i<n;i++){
int u,k,v;
cin>>u>>k;
for(int j=0;j<k;j++){
cin>>v;
G[u][v]=1;
}
}
dfs(1);
while(true){
int f=1,next=0;

	for(int j=1;j<=n;j++){
		if(used[j]==0){
		f=0,next=j;
		break;
		}
	}

if(f)break;
else dfs(next);
}
for(int i=1;i<=n;i++){
	printf("%d %d %d\n",i,s[i],f[i]);
}
return 0;
}

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

int main(){
	int n;
	cin>>n;
	vector<vector<int> > A(n);//????????????????????????-1?????\???????????????
	//??\???
	REP(i,n){
		int u,k;
		cin>>u>>k;
		A[i]=vector<int>(k,0);
		REP(j,k){
			int l;
			cin>>l;
			A[i][j] = l-1;
		}
	}
	//??¢?´¢
	stack<int> s;//??????????????????????????\???
	vector<int> dis(n,0);//??????????????????????????????
	vector<int> fin(n,0);//???????????????????????????
	int time=0;
	while(find(dis.begin(),dis.end(), 0) != dis.end()){
		int saisyo = find(dis.begin(),dis.end(), 0) -  dis.begin();
		//cout<<saisyo<<endl;
		s.push(saisyo);//?????????0???????????????
		while(!s.empty()){
		//REP(ss,3){
			int k = s.top();//??????????????????????????????
			if(dis[k]==0){
				time++;
				dis[k]=time;
				//cout<<"dis "<<k<<" / time "<<time<<endl;
			}
			bool isfinish=true;
			for(int i: A[k]){
				//cout<<"?????????"<<i<<endl;
				if(fin[i]==0 && i!=k){
					s.push(i);
					isfinish=false;
					break;
				}
			}
			if(isfinish){
				time++;
				fin[k]=time;
				s.pop();
				//cout<<"fin "<<k<<" / time "<<time<<endl;
			}
		}
	}
	REP(i,n){
		cout<<i+1<<" "<<dis[i]<<" "<<fin[i]<<endl;
	}
	return 0;
}