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<queue>
#include<map>
#include<stack>
#include<cmath>
#include<iomanip>
#include<set>
#include<numeric>
#include<sstream>
#include<random>
using namespace std;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < n; ++i)
#define rrep(i, st, n) for (int i = st; i < n; ++i)
using pii = pair<int, int>;
const int inf = 1e9 + 7;
int dy[] = {0, 0, -1, 1};
int dx[] = {1, -1, 0, 0};

int n;
int table[101][101];
int reached[101];
int back[101];
int bn = 1;
int cost = 1;
void dfs(int now) {
    //cout << bn << " " << now << " " << cost << endl;
    rrep(i, 1, n + 1) {
        if (table[now][i] == 1 && reached[i] == 0) {
            cost++;
            reached[i] = cost;
            bn = now;
            dfs(i);
        }
    }
    
    cost++;
    //cout << now << " " << cost << endl;
    back[now] = cost;
    return;
}
int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cin >> n;
    rep(i, n + 1) rep(j, n + 1) table[i][j] = 0;
    rep(j, n) {
        int u, k; cin >> u >> k;
        int v;
        rep(l, k) {
            cin >> v;
            table[u][v] = 1;
        }
    }
    reached[1] = 1;
    dfs(1);
    rrep(i, 2, n + 1) {
        if (reached[i] == 0) {
            reached[i] = ++cost;
            dfs(i);
        }
    }
    rrep(i, 1, n + 1) cout << i << " " << reached[i] << " " << back[i] << endl;
    
}

C++: // C++ 14
#include <iostream>
#include <string>
#include <vector>
#include <list>
#include <algorithm>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <unordered_map>
#include <math.h>

#define ll long long
#define Int ll
#define loop(__x, __start, __end) for(Int __x = __start; __x < __end; __x++)
#define loopdown(__x, __start, __end) for(Int __x = __start; __x > __end; __x--)
#define rep(__n) for(Int __x = 0; __x < __n; __x++)
#define span(__a,__x,__y) __a.begin()+__x,__a.begin()+__y
#define span_all(__a) __a.begin(),__a.end()
#define len(__x) (__x.size())
#define last(__x) (__x[__x.size()-1])

using namespace std;

struct Point {
  Int x, y;
  Point(Int x, Int y): x(x), y(y) {}
  Point(): x(0), y(0) {}

  bool operator< (const Point &p1) const {
    return x < p1.x && y < p1.y;
  }
};
ostream & operator << (ostream & out, Point const & v) {
  out << "Point(" << v.x << ", " << v.y << ')';
  return out;
}

istream & operator >> (istream & in, Point & v) {
  Int x, y;
  in >> x; in >> y; v.x = x; v.y = y;
  return in;
}

// Geometry

#define EPS 0.0000000001

class Vector2 {
public:
  double x, y;
  
  Vector2(double x = 0, double y = 0): x(x), y(y) {}
  
  Vector2 operator + (Vector2 v) { return Vector2(x + v.x, y + v.y); }
  Vector2 operator - (Vector2 v) { return Vector2(x - v.x, y - v.y); }
  Vector2 operator * (double k) { return Vector2(x * k, y * k); }
  Vector2 operator / (double k) { return Vector2(x / k, y / k); }
  
  double length() { return sqrt(norm()); }
  double norm() { return x * x + y * y; }
  double dot (Vector2 v) { return x * v.x + y * v.y; }
  double cross (Vector2 v) { return x * v.y - y * v.x; }
  
  bool operator < (const Vector2 &v) const {
    return x != v.x ? x < v.x : y < v.y;
  }
  
  bool operator == (const Vector2 &v) const {
    return fabs(x - v.x) < EPS && fabs(y - v.y) < EPS;
  }
};

ostream & operator << (ostream & out, Vector2 const & v) { 
  out<< "Vector2(" << v.x << ", " << v.y << ')';
  return out;
}

istream & operator >> (istream & in, Vector2 & v) { 
  double x, y;
  in >> x;
  in >> y;
  v.x = x;
  v.y = y;
  return in;
}

Int N, t = 1;
vector<vector<Int> > G(101);
vector<Int> D(101, -1), F(101, -1);

void input() {
  cin >> N;
  Int v, c, u;
  rep(N) {
    cin >> v >> c; v--;
    rep(c) {
      cin >> u; u--;
      G.at(v).push_back(u);
    }
  }
}

void dfs(Int n) {
  if (D.at(n) >= 0) return;
  D.at(n) = t++;
  for (auto v: G.at(n)) {
    dfs(v);
  }
  F.at(n) = t++;
  return;
}

void solve() {
  for (int i=0; i<N; i++) dfs(i);
  for (int i=0; i<N; i++) {
    cout << (i+1) << " " << D.at(i) << " " << F.at(i) << endl;
  }
}

int main() {
  input();
  solve();
  return 0;
}

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

int DFS(vector<vector<int> >& G,
        vector<pair<int, int> >& rec, int i, int t) {
    rec[i].first = t;
    for (int j = 1; j <= G[i].size(); j++) {
        if (G[i][j] && rec[j].first == -1) {
            t = DFS(G, rec, j, t + 1);
        }
    }
    rec[i].second = t + 1;
    return rec[i].second;
}

int main(){
    int n;
    cin >> n;
    vector<vector<int> > G(n + 1, vector<int>(n + 1, 0));
    for (int i = 1; i <= n; i++) {
        int num, k;
        cin >> num >> k;
        for (int j = 0; j < k; j++) {
            int v;
            cin >> v;
            G[i][v] = 1;
        }
    }
    vector<pair<int, int> > record(n + 1, make_pair(-1, -1));
    DFS(G, record, 1, 1);

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

    return 0;
}