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 <array>
#include <vector>
#include <deque>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <string>
#include <algorithm>
#include <numeric>
#include <functional>
#include <iterator>
#include <tuple>
#include <utility>
#include <limits>
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cstdint>
#include <cassert>

using namespace std;

#define FOR(i, start, end) for(int i = (start); i < (end); ++i)
#define REP(i, n) FOR(i, 0, n)

int n;
int mat[100][100];
int d[100];
int f[100];

int dfs(int i, int t)
{
    d[i] = t++;

    REP(j, n) {
        if(mat[i][j] && !d[j]) {
            t = dfs(j, t);
        }
    }

    f[i] = t++;

    return t;
}

void solve()
{
    int t = 1;

    REP(i, n) {
        if(d[i]) continue;

        t = dfs(i, t);
    }
}

int main()
{
    cin >> n;

    REP(i, n) {
        REP(j, n) {
            mat[i][j] = 0;
        }
    }

    REP(_, n) {
        int u, k;
        cin >> u >> k;

        REP(_, k) {
            int v;
            cin >> v;
            mat[u-1][v-1] = 1;
        }
    }

    fill(begin(d), end(d), 0);
    fill(begin(f), end(f), 0);
    solve();

    REP(i, n) {
        cout << i+1 << " " << d[i] << " " << f[i] << "\n";
    }

    return 0;
}

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

const int N = 100;
int M[N][N];
int n;
int t;
int color[N];
int d[N], f[N];

void init(){
  for(int i=0;i<n;i++){
    color[i] = 0;
  }
}

void dfs(int x){
  color[x] = 1;
  d[x] = ++t;
  for(int i=0;i<n;i++){
    if(M[x][i] == 1 && color[i] == 0){
      dfs(i);
    }
  }
  color[x] = 2;
  f[x] = ++t;
}

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

C++: #include <bits/stdc++.h>
using namespace std;
int n, u;
int k[110];
int a[110][110];
int b[110];
int d[110], f[110];
int t=1;

void dfs(int v)
{
	d[v]=t;
	t++;
	b[v]++;
	for(int l=0; l<k[v]; l++)
	{
		if(b[a[v][l]]==0)
		{
			dfs(a[v][l]);
		}
	}
	f[v]=t;
	t++;
}

int main() 
{
	cin >> n;
	for(int i=0; i<n; i++)
	{
		cin >> u;
		cin >> k[u];
		for(int j=0; j<k[u]; j++)
		{
			cin >> a[u][j];
		}
	}
	for(int v=1; v<=n; v++)
	{
		if(b[v]==0)
		{
			dfs(v);
		}
		cout << v << ' ' << d[v] << ' ' << f[v] << endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define REP(i, n) for(int i = 0; i < (n); ++i)
#define SORT(v) sort(v.begin(), v.end());
#define pb(a) push_back(a)
using ll = long long;
using namespace std;

#define WHITE 1
#define GRAY 2
#define BLACK 3

int now, n, u, k, v, tree[102][102], timeTable[102][2], color[102], timeNow = 1;
stack<int> st;

void dfs(){
    while(1){
        if(st.empty()){
          	int l = 1;
          	while(1){
              	if(l == n + 1){
                	FOR(l, 1, n + 1){
                		cout << l << " " << timeTable[l][0] << " " << timeTable[l][1] << endl;
            		}
                  	break;
                }
            	if(color[l] == WHITE){
                	st.push(l);
                  	timeNow++;
                  	break;
                }
              	l++;
            }
          	if(l == n + 1){
            	break;
            }
        }else{
            now = st.top();
          	if(color[now] == WHITE){
            	timeTable[now][0] = timeNow;
            }
            color[now] = GRAY;
            int cnt = 1;
            while(1){
                if(cnt == n + 1){
                    st.pop();
                    color[now] = BLACK;
                    timeTable[now][1] = timeNow + 1;
                    break;
                }else if(tree[now][cnt] && color[cnt] == WHITE){
                    st.push(cnt);
                    break;
                }
                cnt++;
            }
            timeNow++;
        }
    }
}

int main(){
    cin >> n;
  	REP(i, 102){
    	REP(j, 102){
        	tree[i][j] = 0;
        }
    }
    REP(i, n){
        cin >> u >> k;
        color[i + 1] = WHITE;
        REP(j, k){
            cin >> v;
            tree[u][v] = 1;
        }
    }
    st.push(1);
    dfs();
  	return 0;
}