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 <cmath>
#include <vector>
#include <string>
#include <map>
#include <algorithm>
#include <tuple>
#include <set>
#include <stack>
#include <queue>
#include <functional>


using namespace std;
using ll = long long;
using ull = unsigned long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vl = vector<ll>;
using pii = pair<int, int>;
using vpii = vector<pii>;
using pci = pair<char, int>;
using vpci = vector<pci>;
using vb = vector<bool>;
#define out(S) cout<<(S)<<endl;
#define REP(i,b) for(int i=0;i<(b);i++)
#define rREP(i,b) for(int i=(b)-1;i>=0;i--)
#define FOR(i,a,b) for(size_t i=(a);i<(b);i++)
#define rFOR(i,a,b) for(int i=(a)-1;i>=(b);i--)
#define Foreach(item,collection) for(auto item:collection)
#define mod(i) ((i) % (ll)(1e9 + 7))
ll modpow(ll i, ll j) { ll tmp = 1; while (j) { if (j % 2)tmp = mod(tmp*i); i = mod(i*i); j /= 2; }return tmp; }
#define divmod(a,b) (mod(a * modpow((ll)b,(ll)(1e9 + 5))))
#define Yes out("Yes")
#define No out("No")
#define NO out("NO")
#define YES out("YES")
#define INF 1e10;
#define ShowAll(collection) for(auto i:collection){out(i);}
#define IfOut(condition,text) if((condition)){out(text);return 0;}
#define IfeOut(condition,itext,etext) if(condition){out(itext);return 0;}else{out(etext);return 0;}
#define GetAuto(_N,vect) {cin>>_N;vect.resize(_N);REP(i,_N){cin>>vect[i];}}
#define beginend(vec) (vec).begin(),(vec).end()
#define pb(item) push_back(item)
#define removeAll(vec,deleg) auto itr=remove_if(beginend(vec),deleg);vec.erase(itr,vec.end());
void removeAt(string& s, int index) { s.erase(index, 1); }
template<typename T> void removeAt(vector<T>& v, int index) { v.erase(v.begin() + index); }
ll manhattanDistance(ll x1, ll y1, ll x2, ll y2) { return (abs(x2 - x1) + abs(y2 - y1)); }
vector<ll> sieveOfEratosthenes(int max) { ll prime; double sqrtmax = sqrt(max); vector<ll> primeVec, searchVec; FOR(i, 2, max + 1) searchVec.push_back(i); do { prime = searchVec[0]; primeVec.push_back(prime); auto itr = remove_if(beginend(searchVec), [=](ll x)->bool {return x%prime == 0; }); searchVec.erase(itr, searchVec.end()); } while (prime < sqrtmax); primeVec.reserve(primeVec.size() + searchVec.size()); primeVec.insert(primeVec.end(), beginend(searchVec)); return primeVec; }
bool isPrime(ll x) { if (x == 2) return true; if (x < 2 || x % 2 == 0) return false; ll i = 3; while (i <= sqrt(x)) { if (x%i == 0) return false; i += 2; }return true; }
vi seq(int max, int start = 0) {vi rt(max - start+1);FOR(i, start, max+1) rt[i] = i;return rt;}
template<typename T> size_t find_first_of(vector<T> v, T val) { auto itrfind = find(beginend(v), val); size_t dis = distance(v.begin(), itrfind); if (dis == v.size()) { return -1; }return dis; }
template<class T> struct Identity {typedef T type;};
template<typename T> vector<T> select(const vector<T> &v, typename Identity<function<T(const T &)>>::type ft) {vector<T> rt; for (T item : v) { rt.push_back(ft(item)); }return rt;}
template<typename T> string join(const vector<T> &v, typename Identity<function<string(const T &)>>::type ft) {string rt = "";Foreach(x, v) {rt += ft(x);}return rt;}

int d[105]{ 0 }, f[105]{ 0 };
int time;
int N;
void dfs(vvi & box,int v) {
	if (d[v] != 0) return;
	d[v] = time++;
	for (int i = 0; i < N; i++) if (box[v][i] != 0) {
		dfs(box,i);
	}
	f[v] = time++;
	return;
}

int main(){
	cin >> N;
	vvi box(N, vector<int>(N, 0));
	time = 1;
	REP(i, N) {
		int v, k, u;
		cin >> v >> k;
		REP(n, k) {
			cin >> u;
			box[i][u-1] = 1;
		}
	}
	dfs(box, 0);

	REP(i, N) {
		cout << i + 1 << " " << d[i] << " " << f[i] << endl;
	}

	return 0;
}

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

static const int MAX_NUM = 100;

void dsf_cal(int matrix[][MAX_NUM + 1], int state[], int time[][2], int index, int num)
{
    static int t = 1;
    stack<int> S;

    S.push(index);
    state[index]   = 1;
    time[index][0] = t;
    ++t;

    while (S.empty() != true) {
        int i;
        int target = S.top();
        for (i = 1; i < num + 1; i++) {
            if (matrix[target][i] == 1) {
                if (state[i] == 0) {
                    S.push(i);
                    state[i]   = 1;
                    time[i][0] = t;
                    ++t;
                    break;
                }
            }
        }
        if (i == num + 1) {
            time[target][1] = t;
            ++t;
            S.pop();
        }
    }

    return;
}

void DSF(int matrix[][MAX_NUM + 1], int num)
{
    int state[MAX_NUM+1]   = {0};
    int time[MAX_NUM+1][2] = {0};

    for (int i = 1; i < num+1; i++) {
        if (state[i] == 0) {
            dsf_cal(matrix, state, time, i, num);
        }
    }

    for (int i = 1; i < num+1; i++) {
        printf("%d %d %d\n", i, time[i][0], time[i][1]);
    }

    return;
}

int main(void)
{
    int num;
    int index, elemNum, tmp;
    int matrix[MAX_NUM + 1][MAX_NUM + 1] = {0};

    scanf("%d", &num);
    for (int i = 0; i < num; i++) {
        scanf("%d %d", &index, &elemNum);
        for (int j = 0; j < elemNum; j++) {
            scanf("%d", &tmp);
            matrix[index][tmp] = 1;
        }
    }

    DSF(matrix, num);

    return 0;
}