Go: package main

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

type vertexId int

type vertex struct {
	id vertexId
	firstVisitAt int
	finishVisitAt int
	adjs []vertexId
}

func createVertex(id int, adjsInt []int) vertex {
	adjs := make([]vertexId, len(adjsInt))
	for i := 0; i < len(adjs); i++ {
		adjs[i] = vertexId(adjsInt[i])
	}
	return vertex{
		id: vertexId(id),
		firstVisitAt: 0,
		finishVisitAt: 0,
		adjs: adjs,
	}
}

func (v *vertex) isVisited() bool {
	return v.firstVisitAt > 0
}

func dfs(currentId vertexId, timestamp int, vertices []vertex) int {
	currentVertex := &vertices[currentId-1]
	if currentVertex.isVisited() {
		return timestamp
	}
	timestamp = timestamp + 1
	currentVertex.firstVisitAt = timestamp
	for _, adjId := range currentVertex.adjs {
		timestamp = dfs(adjId, timestamp, vertices)
	}
	timestamp = timestamp + 1
	currentVertex.finishVisitAt = timestamp
	return timestamp
}

func solveDfs(vertices []vertex) {
	timestamp := 0
	for {
		vid := vertexId(-1)
		for i := 0; i < len(vertices); i++ {
			if !vertices[i].isVisited() {
				vid = vertexId(i+1)
				break
			}
		}
		if vid > 0 {
			timestamp = dfs(vid, timestamp, vertices)
		} else {
			break
		}
	}
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}

	vertices := make([]vertex, n)
	for i := 0; i < n; i++ {
		id, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjN, err := nextInt(sc)
		if err != nil {
			panic(err)
		}
		adjs := make([]int, adjN)
		for j := 0; j < adjN; j++ {
			adjId, err := nextInt(sc)
			if err != nil {
				panic(err)
			}
			adjs[j] = adjId
		}
		vertices[i] = createVertex(id, adjs)
	}

	solveDfs(vertices)

	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", vertices[i].id, vertices[i].firstVisitAt, vertices[i].finishVisitAt)
	}
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

func nextInt(sc *bufio.Scanner) (int, error) {
	return strconv.Atoi(nextText(sc))
}

C++: #include <cstdio>

typedef struct timestamp {
        int d, f;
} timestamp;

const int N = 100;
bool graph[N][N] {{false}};
timestamp ts[N];
int time = 0;

void search(int n, int cur) {
        if (ts[cur].d) {
                return;
        }
        ts[cur].d = ++time;
        for (int i = 0; i < n; i++) {
                if (graph[cur][i]) {
                        search(n, i);
                }
        }
        ts[cur].f = ++time;
}

int main() {
        int n, u, k, v;
        for (int i = 0; i < N; i++) {
                ts[i].d = ts[i].f = 0;
        }

        scanf("%d", &n);
        for (int i = 0; i < n; i++) {
                scanf("%d %d", &u, &k);
                for (int j = 0; j < k; j++) {
                        scanf("%d", &v);
                        graph[u-1][v-1] = true;
                }
        }
        for (int cur = 0; cur < n; cur++) {
                search(n, cur);
        }
        for (int i = 0; i < n; i++) {
                printf("%d %d %d\n", i+1, ts[i].d, ts[i].f);
        }

        return 0;
}

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

using namespace std;

const int N = 100;
bool G[N][N];
enum Color {WHITE, BLACK, GRAY} color[N];
int d[N], f[N];
int tt;
int n;

void dfs(int u) {
    color[u] = GRAY;
    d[u] = ++tt;
    for (int v = 0; v < n; ++v) {
        if (G[u][v] && color[v] == WHITE) {
            dfs(v);
        }
    }
    color[u] = BLACK;
    f[u] = ++tt;
}

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

    for (int i = 0; i < n; ++i) {
        int u, k;
        scanf("%d %d", &u, &k);
        --u;
        for (int j = 0; j < k; ++j) {
            int v;
            scanf("%d", &v);
            --v;
            G[u][v] = true;
        }
    }
    for (int u = 0; u < n; ++u) {
        if (color[u] == WHITE)
            dfs(u);
    }
    for (int u = 0; u < n; ++u) {
        cout << u + 1 << " " << d[u] << " " << f[u] << endl;
    }
}

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

typedef long long ll;
typedef vector<long long> vll;
typedef vector<int> vi;
typedef pair<int, int> pi;

#define yes "Yes"
#define yse "Yes"
#define no "No"

#define pb push_back
#define mp make_pair

#define NIL -1

#define list_itr list<ll>::iterator

#define rep(i, l, n) for (int i = (l); i < n; i++)
#define rep_cs(i, l, n) for (int i = (l); i <= n; i++)
#define rep_d(j, n) for (int j = n; j >= 0; j--)
#define rep_d_op(j, n, a) for (int j = n; j >= a; j--)

template <class T>
inline bool chmax(T &a, T b)
{
    if (a < b)
    {
        a = b;
        return 1;
    }
    return 0;
}
template <class T>
inline bool chmin(T &a, T b)
{
    if (a > b)
    {
        a = b;
        return 1;
    }
    return 0;
}

const int MOD = 1000000007;
const vector<int> dx = {1, 0};
const vector<int> dy = {0, 1};
const ll INF = 1LL << 60;

// int max = *std::max_element(v.begin(), v.end());
// int sum = accumulate(v, v + v.size(), 0);

int GCD(int a, int b) { return b ? GCD(b, a % b) : a; }

using Graph = vector<vector<int>>;
Graph G;
vector<bool> seen;

bool binary_search(int a[], int n, int key)
{
    int l = 0;
    int r = n;
    int middle;
    while (l < r)
    {
        middle = (l + r) / 2;
        if (key == a[middle])
        {
            return true;
        }

        if (key > a[middle])
        {
            l = middle + 1;
        }
        else if (key < a[middle])
        {
            r = middle;
        }
    }
    return false;
}

static const int N = 100;
static const int WHITE = 0;
static const int GRAY = 1;
static const int BLACK = 2;

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

int next(int u)
{
    rep(v, nt[u], n)
    {
        nt[u] = v + 1;
        if (M[u][v])
        {
            return v;
        }
    }
    return -1;
}

void dfs_visit(int r)
{
    rep(i, 0, n)
    {
        nt[i] = 0;
    }

    stack<int> S;
    S.push(r);
    color[r] = GRAY;
    d[r] = ++tt;

    while (!S.empty())
    {
        int u = S.top();
        int v = next(u);
        if (v != -1)
        {
            if (color[v] == WHITE)
            {
                color[v] = GRAY;
                d[v] = ++tt;
                S.push(v);
            }
        }
        else
        {
            S.pop();
            color[u] = BLACK;
            f[u] = ++tt;
        }
    }
}

void dfs()
{
    rep(i, 0, n)
    {
        color[i] = WHITE;
        nt[i] = 0;
    }
    tt = 0;

    rep(u, 0, n)
    {
        if (color[u] == WHITE)
        {
            dfs_visit(u);
        }
    }

    rep(i, 0, n)
    {
        cout << i + 1 << " " << d[i] << " " << f[i] << endl;
    }
}

int main()
{
    int u, k, v;
    cin >> n;

    rep(i, 0, n)
    {
        rep(j, 0, n)
        {
            M[i][j] = 0;
        }
    }

    rep(i, 0, n)
    {
        cin >> u >> k;
        u--;
        rep(j, 0, k)
        {
            cin >> v;
            v--;
            M[u][v] = 1;
        }
    }

    dfs();
}

C++: #include <bits/stdc++.h>
using namespace std;
const int N = 101;
int v[N][N]={0};
int stt[N]={0};
int fit[N]={0};
int t=0;

void dfs(int n){
	if(stt[n]!=0) return;
	stt[n] = ++t;
	for(int i=0;i<v[n][1];i++){
		dfs(v[n][i+2]);
	}
	fit[n]=++t;
}

int main(){
	int n;
	cin >> n;
	for(int i=0;i<n;i++){
		int u,k;
		cin >> u >> k;
		v[u][0]=i+1;
		v[u][1]=k;
		for(int j=0;j<k;j++){
			int a;
			cin >> a;
			v[u][j+2]=a;
		}
	}
	for(int i=1;i<=n;i++)dfs(i);
	for(int i=1;i<n+1;i++){
		cout << i << " " <<stt[i] << " " << fit[i] << endl;
	}
    return 0;
}