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 <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <climits>

using namespace std;

const int WHITE=0, GRAY=1, BLACK=2;

struct DFS {
    int n;
    vector<vector<int>> g;
    vector<int> discover;
    vector<int> finish;
    vector<int> state;
    int time = 1;
    
    DFS(int n):n(n) {
        g.assign(n, vector<int>());
        discover.assign(n, -1);
        finish.assign(n, -1);
        state.assign(n, WHITE);
    }
    
    void addEdge(int u, int v) {
        g[u].push_back(v);
    }
    
    void solve() {
        for (int i = 0; i < n; i++) {
            if (state[i] == WHITE) {
                dfs(i);
            }
        }
    }
    
    void dfs(int u) {
        state[u] = GRAY;
        discover[u] = time++;
        for (int v : g[u]) {
            if (state[v] == WHITE) {
                dfs(v);
            } 
        }
        finish[u] = time++;
        state[u] = BLACK;
    }
    
    void print() {
        for (int i = 0; i < n; i++) {
            cout << i << ":";
            for (int v : g[i]) {
                cout << v << " ";
            }
            cout << endl;
        }
    }
};

int main() {
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    DFS dfs(n);
    for (int i = 0; i < n; i++) {
       int u, k;
       cin >> u >> k;
       u--;
       for (int j = 0; j < k; j++) {
           int v;
           cin >> v;
           v--;
           dfs.addEdge(u, v);
       }
    }
    
    //dfs.print();
    
    dfs.solve();
    
    for (int i = 0; i < n; i++) {
        cout << (i + 1) <<  " " << dfs.discover[i] << " " << dfs.finish[i] << endl; 
    }
    
    return 0;
}

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

int n;
int g[101][101];
char c[101];
int visit[101];
int finish[101];
int main() {
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        int u, k;
        cin >> u >> k;
        for (int j = 0; j < k; ++j) {
            int v;
            cin >> v;
            g[u][v] = 1;
        }

    }

   stack<int> s;
    for (int l = 1; l <= n; ++l) {
        c[l] = 'w';

    }
    int time = 0;
    int start = 0;
    int v;
    while(true) {
        start++;
        if(start == n) break;
        if(c[start] == 'w') {
            time++;
            s.push(start);
            c[start] = 'g';
            visit[start] = time;
            while (s.size() != 0) {
                time++;
                v = s.top();
                int next = -1;
                for (int i = 1; i <= n ; ++i) {
                    if(i == v) {
                        continue;
                    }
                    if(g[v][i] && c[i] == 'w') {
                        next = i;
                        break;
                    }
                }
                if(next == -1) {
                    c[v] = 'b';
                    finish[v] = time;
                    s.pop();
                } else {
                    c[next] = 'g';
                    visit[next] = time;
                    s.push(next);
                }
            }
        }
    }

    for (int m = 1; m <= n; ++m) {
        cout << m << " " << visit[m ] << " " << finish[m] << endl;

    }



    return 0;
}

C++: #include <iostream>
#include <stack>
using namespace std;
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 dfs_visit(int u)
{
    int v;
    color[u] = GRAY;
    d[u] = ++tt;
    for (int v = 0; v < n; v++)
    {
        if (M[u][v] == 0)
        {
            continue;
        }
        if (color[v] == WHITE)
        {
            dfs_visit(v);
        }
    }
    color[u] = BLACK;
    f[u] = ++tt;
}

int dfs()
{
    int u;
    for (int u = 0; u < n; u++)
    {
        color[u] = WHITE;
    }
    tt = 0;
    for (int u = 0; u < n; u++)
    {
        if (color[u] == WHITE)
        {
            dfs_visit(u);
        }
    }
    for (int u = 0; u < n; u++)
    {
        cout << u + 1 << " " << d[u] << " " << f[u] << endl;
    }
}

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

    for (int i = 0; i < n; i++)
    {
        cin >> u >> k;
        u--;
        for (int j = 0; j < k; j++)
        {
            cin >> v;
            v--;
            M[u][v] = 1;
        }
    }

    dfs();
    return 0;
}

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) {
        ts[cur].d = ++time;
        for (int i = 0; i < n; i++) {
                if (graph[cur][i] && !ts[i].d) {
                        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;
                }
        }
        int cur = 0;
        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;
}