Go: package main

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

//util
var sc = bufio.NewScanner(os.Stdin)

func nextStr() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func printList(list []int) {
	n := len(list)
	buf := bufio.NewWriter(os.Stdout)
	for _, v := range list[0 : n-1] {
		buf.Write([]byte(fmt.Sprintf("%d ", v)))
	}
	buf.Write([]byte(fmt.Sprintf("%d\n", list[n-1])))
	buf.Flush()
}

func max(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func min(a, b int) int {
	if a > b {
		return b
	} else {
		return a
	}
}

//solve

const MAX = 100
const WHITE = 0
const GRAY = 1
const BLACK = 2

var time, n int

//隣接行列
var M [MAX][MAX]int

//d[i]: 最初にiを訪問した時刻。発見時刻
//f[i]: iの隣接リストを訪問し終えた時刻。完了時刻
var color, d, f [MAX]int

func dfs_visit(u int) {
	color[u] = GRAY
	time++
	d[u] = time
	//隣接を調べる
	for v := 0; v < n; v++ {
		if M[u][v] == 0 {
			continue
		}
		//隣接するvが、未訪問だった場合
		if color[v] == WHITE {
			dfs_visit(v)
		}
	}
	//訪問完了処理
	color[u] = BLACK
	time++
	f[u] = time
	//訪問完了
}

func dfs() {
	//初期化
	for u := 0; u < n; u++ {
		color[u] = WHITE
	}
	time = 0

	//未訪問のuを始点として、深さ優先探索
	for u := 0; u < n; u++ {

		if color[u] == WHITE {
			dfs_visit(u)
		}
	}

	for u := 0; u < n; u++ {
		fmt.Println(u+1, d[u], f[u])
	}
}

func main() {
	sc.Split(bufio.ScanWords)
	n = nextInt()
	for i := 0; i < n; i++ {
		u, k := nextInt(), nextInt()
		M[u-1][u-1] = 0

		//fmt.Println(u, k)
		if k > 0 {
			for j := 0; j < k; j++ {

				v := nextInt()
				M[u-1][v-1] = 1

			}
		}

	}

	dfs()

}

C++: #include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cassert>
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define rep(i,n) FOR(i,0,n)
#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define vint vector<int>
#define vdouble vector<double>
#define vstring vector<string>
using namespace std;

#include<map>
#include<set>
#include<queue>

typedef long long ll;
typedef unsigned long long ull;

const int MAX_N = 1000000;

int N;
vint G[100];
int FLG[100];
int D[100];
int F[100];
const int NIL = -1;
int tt;

void dfs(int ii){

	tt++;
	D[ii] = tt;

	// cout << "reach " << ii << " " << tt << endl;

	rep(i, G[ii].size()){
		int to = G[ii][i];
		if (D[to] == NIL){
			dfs(to);
		}
	}

	tt++;
	F[ii] = tt;
	// cout << "back " << ii << " " << tt << endl;

}

void run_dfs(){
	rep(i, N){ D[i] = NIL; }
	int start = 0;
	tt = 0;
	rep(i, N){
		if (D[i] == NIL) dfs(i);
	}
}

int main() {

	cin >> N;
	rep(i, N){
		int id, n; cin >> id >> n; id--;
		rep(j, n){
			int id_to; cin >> id_to; id_to--;
			G[id].push_back(id_to);
		}
	}

	run_dfs();

	rep(i, N){
		cout << i << " " << D[i] << " " << F[i] << endl;
	}
}

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

#define mp       make_pair
#define pb       push_back
#define all(x)   (x).begin(),(x).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define repi(i,a,b) for(int i = (a); i < (b); i++)

using namespace std;

typedef    long long          ll;
typedef    unsigned long long ull;
typedef    vector<bool>       vb;
typedef    vector<int>        vi;
typedef    vector<vb>         vvb;
typedef    vector<vi>         vvi;
typedef    pair<int,int>      pii;

const int INF=1<<29;
const double EPS=1e-9;

const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
vector<int> d[120];
bool visit[120];
int cnt = 0;
int fin[120];
int st[120];
void dfs(int p){
	cnt++;
	st[p]=cnt;
	//cout <<"p = "<<p<<" cnt = "<<cnt<<endl;
	visit[p]=true;
	for(int i =0;i <d[p].size();i++){
		if(!visit[d[p][i]]){
			dfs(d[p][i]);
		}
	}
	cnt++;
	fin[p]=cnt;

}
int main(){
	int n;
	cin>>n;
	memset(visit, false, sizeof(visit));
	for(int i =0;i < n;i++){
		int u,k;
		cin>>u>>k;
		for(int j =0;j < k;j++){
			int c;
			cin>>c;
			d[u].push_back(c);
		}
	}
	dfs(1);
	for(int i =1;i <=n;i++){
		cout <<i<<" "<<st[i]<<" "<<fin[i]<<endl;
	}
	return 0;
}

C++: #include <utility>
#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;
vector <int> m[103];
int kakunin[103]={0};
int d[103];
int f[103];
int cnt=1;
void dfs(int num){
    d[num]=cnt++;
    for(int i=0;i<m[num].size();i++){
        if(kakunin[m[num][i]]==0){kakunin[m[num][i]]=1;dfs(m[num][i]);}}
    f[num]=cnt++;
}
int main() {
    int n,a,tmp,id;
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>id;
        cin>>a;
        for(int j=0;j<a;j++){
            scanf("%d",&tmp);
            m[id].push_back(tmp);
        }
    }
    dfs(1);
    for(int i=1;i<=n;i++){
        cout<<i<<" "<<d[i]<<" "<<f[i];}
}

C++: #include <iostream>


int D[100];
int F[100];
int V[100][100];

int cnt = 0;
int n;

void dfs(int r) {
    D[r] = ++cnt;
    for (int i = 0; i < n; i++) {
        if ((V[r][i] == 1) && (D[i] == 0)) {
            dfs(i);
        }
    }
    F[r] = ++cnt;
}

int main() {
    std::cin >> n;
    for (int i = 0; i < n; i++) {
        int id, e_num;
        std::cin >> id >> e_num;
        for (int j = 0; j < e_num; j++) {
            int t;
            std::cin >> t;
            V[id - 1][t - 1] = 1;
        }
    }

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

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

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){
	if(cnt<=25)cout<<now<<endl;
	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);
	for(int i=1;i<=n;i++)cout<<used[i]<<" ";cout<<endl;
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<iostream>
#include<set>
using namespace std;
#define MAX 101

int t = 1, used[MAX];
pair<int,int> ans[MAX];
set<int> G[MAX];

void dfs(int id){
	if(used[id] == true) return ;
	else used[id] = true;
	ans[id].first = t++;
	
	for(int y : G[id]){
		dfs(y);
	}
	ans[id].second = t++;
}

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