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++: // Ref : https://book.mynavi.jp/ec/products/detail/id=35408

#include <iostream>
using namespace std;

static const int N = 100;
int G[N][N] = { {} };
int n, t = 0;
int detected_t[N] = {};
int finished_t[N] = {}; 

void depthFirstSearch(int ix) {
	if (!detected_t[ix - 1]) {
		detected_t[ix - 1] = ++t;
		for (int j = 0; G[ix - 1][j]; j++) {
			depthFirstSearch(G[ix - 1][j]);
		}
		if (!finished_t[ix - 1]) finished_t[ix - 1] = ++t;
	}
}

void myCheck() {
	for (int i = 0; i < n; i++) {
		cout << "index " << i + 1 << " : ";
		for (int j = 0; G[i][j]; j++) {
		if (j) cout << " ";
		cout << G[i][j];
		}
		cout << " time " << detected_t[i] << ", " << finished_t[i] << endl;
	}
}

int main() {
	int ix, deg;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> ix >> deg;
		for (int j = 0; j < deg; j++) cin >> G[ix - 1][j];
	}

	depthFirstSearch(1);
	//myCheck();

	for (int i = 0; i < n; i++) cout << i + 1 << " " << detected_t[i] << " " << finished_t[i] << endl;

	return 0;
}

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

vector<vector<int>> G;
vector<int> used;
vector<int> found;
vector<int> done;

int dfs(int v, int t){
    if(!used[v]){
        used[v] = 1;
        found[v] = t;
    }
    for(long long i=0; i<G[v].size(); i++){
        int nv = G[v][i];
        if(used[nv]) continue;
        else{
            t = dfs(nv, ++t);
        }
    }
    return done[v] = ++t;
}

int main(){
    int N; cin>>N;
    G.resize(N);
    used.resize(N, 0);
    found.resize(N, 0);
    done.resize(N, 0);
    found[0] = 1;
    for(long long i=0; i<N; i++){
        int u, k; cin >> u >>k;
        u--;
        G[u].resize(k);
        for(long long j=0; j<k; j++){
            int v; cin >> v;
            v--;
            G[u][j] = v;
        }
    }
    dfs(0, 1);
    for(long long i=0; i<N; i++){
        cout << i+1 << " " << found[i] << " " << done[i] << endl;
    }
    return 0;
}

C++: /* ALDS1_11_B: Depth First Search */

#include <iostream>
#include <cstdio>
#include <vector>
using std::vector;

vector<int> *graph;
int elapsed = 1;

// Search the graph recursively by depth-first search.
void traverse(int id, int found[], int finished[]) {
    if (0 < found[id]) {
        return;
    }

    found[id] = elapsed++;
    vector<int> adjs = graph[id];
    for (int i = 0; i < adjs.size(); i++) {
        traverse(adjs[i], found, finished);
    }
    finished[id] = elapsed++;
}

int main() {
    int n_v;
    scanf("%d", &n_v);

    int max_v = n_v + 1;
    graph = new vector<int>[max_v];

    for (int i = 0; i < max_v; i++) {
        int id, n_adjs;
        scanf("%d %d", &id, &n_adjs);

        for (int j = 0; j < n_adjs; j++) {
            int adj_id;
            scanf("%d", &adj_id);
            graph[id].push_back(adj_id);
        }
    }

    int found[max_v];
    int finished[max_v];
    std::fill_n(found, max_v, 0);
    std::fill_n(finished, max_v, 0);

    for (int id = 1; id < max_v; id++) {
        traverse(id, found, finished);
    }

    for (int id = 1; id < max_v; id++) {
        printf("%d %d %d\n", id, found[id], finished[id]);
    }
    return 0;
}

C++: #include<algorithm>
#include<bitset>
#include<iostream>
#include<iomanip>
#include<set>
#include<string>
#include<math.h>

using namespace std;

class zahyo{
	public:
	int x;
	int y;
	zahyo(){
		x=0;
		y=0;
	}
	zahyo(int x_,int y_){
		x=x_;
		y=y_;
	}
	void print(){
		cout<<x<<" "<<y;
	}
	zahyo operator+(zahyo add){
		add.x=this->x+add.x;
		add.y=this->y+add.y;
		return add;
	}
	zahyo operator-(zahyo add){
		add.x=this->x-add.x;
		add.y=this->y-add.y;
		return add;
	}
	bool operator==(const zahyo add) const{
		if(add.x==this->x and add.y==this->y){return true;}
		else{return false;}
	}
	bool operator!=(const zahyo add) const{
		if(add.x==this->x or add.y==this->y){return false;}
		else{return true;}
	}
	bool operator<(const zahyo add) const{
		if(this->x<add.x){return true;}
		else if(this->x==add.x and this->y<add.y){return true;}
		else{return false;}
	}
	bool operator>(const zahyo add) const{
		if(this->x>add.x){return true;}
		else if(this->x==add.x and this->y>add.y){return true;}
		else{return false;}
	}
	void input(){
		cin>>x>>y;
	}
};

int n;
int counter=0;
int glaph[100][100]={{}};
int ans[100][2]={{}};
void depthsearch(int t){
	counter++;
	ans[t][0]=counter;
	for(int i=0;i<n;i++){
		if(glaph[t][i]==1 and ans[i][0]==0){
			depthsearch(i);
		}
	}
	counter++;
	ans[t][1]=counter;
}

int main(){
	cin>>n;
	for(int i=0;i<n;i++){
		int k;
		cin>>k;
		cin>>k;
		for(int j=0;j<k;j++){
			int l;
			cin>>l;
			l--;
			glaph[i][l]=1;
		}
	}
	for(int i=0;i<n;i++){
		if(ans[i][0]==0){
			depthsearch(i);
		}
	}
	for(int i=0;i<n;i++){
		cout<<(i+1)<<" "<<ans[i][0]<<" "<<ans[i][1]<<endl;
	}
}

C++: #include <iostream>
#include <vector>

using namespace std;

void dfs(vector<vector<int>>& graph, int vertex, vector<bool>& marked, vector<int>& d, vector<int>& f, int& time) {
    if (marked[vertex])
        return;
    marked[vertex] = true;
    d[vertex] = ++time;
    for (int x: graph[vertex])
        if (!marked[x])
            dfs(graph, x, marked, d, f, time);
    f[vertex] = ++time;
}

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

    vector<vector<int>> graph;
    for (int i = 0; i < n; i++) {
        vector<int> t;
        int u;
        cin >> u;
        int k;
        cin >> k;
        for (int j = 0; j < k; j++) {
            int v;
            cin >> v;
            t.push_back(v - 1);
        }
        graph.push_back(t);
    }

    vector<bool> marked(n);
    vector<int> d(n);
    vector<int> f(n);
    int time = 0;

    for (int i = 0; i < n; i++)
        dfs(graph, i, marked, d, f, time);
    for (int i = 0; i < n; i++)
        cout << i + 1 << " " << d[i] << " " << f[i] << endl;

    return 0;
}