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)
	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>
#define rep(i, start, end) for (long long i = start; i < end; ++i)
#define srt(x) sort((x).begin(), (x).end());
#define rsrt(x) sort((x).rbegin(), (x).rend());
#define deb(x) cout<<#x<<" = "<<(x)<<" (L"<<LINE<<")"<<endl;
#define vdeb(x) {cout<<#x<<" = { "; rep(i, x.size()) cout<<x[i]<<' '; cout <<'}'<<" (L"<<LINE<<")"<<endl;}
using namespace std;
using ll = long long;
using ld = long double;
using vi = vector<int>;
using vivi = vector<vi>;
using vll = vector<long long>;
using vllvll = vector<vll>;
using vs = vector<string>;
using um = unordered_map<long long, long long>;
const long long INF = 1LL << 60;
const long long MOD = 1e9 + 7;
const long long MAX = 1000;

ll n;
vllvll M(MAX,vll(0));
vll ts1(MAX);
vll ts2(MAX);
vll seen(MAX, 0);

void rec(ll node, ll& ptr)
{
    ts1[node] = ptr++;
    seen[node] = 1;
    for (ll adj : M[node]) {
        if (seen[adj] == 1) continue;
        rec(adj, ptr);
    }
    ts2[node] = ptr++;
}

void dfs()
{
    ll ptr = 1;
    rep(i, 0, n) {
        if (seen[i] == 0) {
            rec(i, ptr);
        }
    }
}

int main()
{
    cin >> n;
    ll u, k, v;
    rep(i, 0, n) {
        cin >> u >> k;
        --u;
        rep(j, 0, k) {
            cin >> v;
            --v;
            M[u].push_back(v);
        }
    }
    ll f = 0, l = 0;
    dfs();
    rep(i, 0, n) {
        cout << i+1 << ' ' << ts1[i] << ' ' << ts2[i]<< endl;
    }
}

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

map<int, vector<int>> A;
int color[101];
int start[101];
int endTime[101];
int elapsed = 0;

void dfs(int u) {
    elapsed++;
    color[u] = 1;
    start[u] = elapsed;
    for (vector<int>::iterator it = A[u].begin(); it != A[u].end(); it++) {
        if (color[*it] == 0) {
            dfs(*it);
        }
    }
    endTime[u] = ++elapsed;
}

int main() {
    int n;
    cin >> n;

    int u, k;
    for (int i = 1; i <= n; i++) {
        color[i] = 0;
        cin >> u >> k;
        int ad;
        for (int j = 0; j < k; j++) {
            cin >> ad;
            A[u].push_back(ad);
        }
    }

    for (int i = 1; i <= n; i++) {
        if (color[i] == 0) dfs(i);
    }

    for (int i = 1; i <= n; i++) {
        cout << i << " " << start[i] << " " << endTime[i] << endl;
    }
}

C++: #include <bits/stdc++.h>
using namespace std;
#define r(i,n) for(auto i=0;i<n;i++)
#define s(c) static_cast<int>((c).size())

struct Timestamp{
	int discovered;
	int finished;
};

int main(){
	int n;
	cin >> n;

	set<int> A[n+1];
	bool reached[n+1]{};
	int v1, v2, deg;
	r(i, n){
		cin >> v1 >> deg;

		r(j, deg){
			cin >> v2;
			A[v1].insert(v2);
			//A[v2].insert(v1);
		}
	}

	Timestamp ts[n+1];
	for(int i = 1; i <= n; i++){
		ts[i].discovered = 0;
		ts[i].finished = 0;
	}
	ts[1].discovered = 1;


	int time = 0;
	stack<int> s;

	while(true){
		for (int i = 1; i <= n; i++) {
			if (reached[i])
				continue;
			reached[i] = true;
			s.push(i);
			time++;
			ts[i].discovered = time;
			goto DFS;
		}
		break;

		DFS:;
		while (!s.empty()) {
			v1 = s.top();

			bool hasNext = false;
			for (int v2 : A[v1]) {
				if (!reached[v2]) {
					reached[v2] = true;
					s.push(v2);
					hasNext = true;
					break;
				}
			}

			if (!ts[v1].discovered) {
				time++;
				ts[v1].discovered = time;
			}

			if (!hasNext) {
				time++;
				ts[v1].finished = time;
				s.pop();
			}
		}
	}

	for(int i = 1; i <= n; i++){
		printf("%d %d %d\n", i, ts[i].discovered, ts[i].finished);
	}

	return 0;
}

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

std::vector<pair<int, int> > stamp(101);
std::vector<std::vector<int> > v(101);
bool isCheckd[101];
int cnt = 0;

void dfs(int k){
	cnt++;
	isCheckd[k] = true;
	stamp[k].first = cnt;
	for(int i=0;i<v[k].size();i++){
		int next = v[k][i];
		if(!isCheckd[next]){
			dfs(next);
		}
	}
	cnt++;
	stamp[k].second = cnt;
}

int main(){
	int n;

	fill(isCheckd,isCheckd+101,false);
	isCheckd[0] = true;
	cin >> n;

	for(int i=0;i<n;i++){
		int u,k;
		cin >> u >> k;
		for(int j=0;j<k;j++){
			int in;
			cin >> in;
			v[u].push_back(in);
		}
	}

	for(int i=0;i<n;i++){
		if(!isCheckd[i])
			dfs(i);
	}


	for(int i=0;i<n;i++){
		cout << i+1 <<" "<< stamp[i+1].first <<" " <<stamp[i+1].second<< endl;
	}

	return 0;
}

C++: #include <stdio.h>
#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

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

void dfs_visit(int u){
	int v;
	color[u]=GRAY;
	d[u]=++tt;
	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(j=0;j<k;j++){
			scanf("%d",&v);
			v--;
			M[u][v]=1;
		}
	}
	
	dfs();
	
	return 0;
}