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 <stack>
using namespace std;
int d[101],f[101],G[101][101];
stack<int>s;
int n,t;
void dfs(int u)
{
    s.push(u);
    d[u]=t++;
    int i;
    while(!s.empty()){
        u=s.top();
        for(i=1;i<=n;i++)
        {
            if(G[u][i]==1 && d[i]==0)
            {
                s.push(i);
                d[i]=t++;
                //u=i;
                break;
            }
        }
        if(i>n)
        {
            f[s.top()]=t++;
            s.pop();
        }
    }
}
int main()
{
    int k,u,v;
    cin>>n;
    for(int i=1;i<=n;i++){
        d[i]=0;
        for(int j=1;j<=n;j++)
            G[i][j]=0;
    }
    for(int i=0;i<n;i++)
    {
        cin>>u>>k;
        for(int j=0;j<k;j++)
        {
            cin>>v;
            G[u][v]=1;
        }
    }
    t=1;
    for(int i=1;i<=n;i++)
    {
        if(d[i]==0)
            dfs(i);
    }
    for(int i=1;i<=n;i++)
    {
        cout<<i<<' '<<d[i]<<' '<<f[i]<<endl;
    }
    return 0;
}

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

#define rep(i, m, n) for(int(i) = (int)(m); i < (int)(n); ++i)
#define rep2(i, m, n) for(int(i) = (int)(n)-1; i >= (int)(m); --i)
#define REP(i, n) rep(i, 0, n)
#define REP2(i, n) rep2(i, 0, n)
#define all(hoge) (hoge).begin(), (hoge).end()
#define en '\n'
using ll = long long;
using ull = unsigned long long;
using ld = long double;
template <class T>
using vec = vector<T>;
template <class T>
using vvec = vector<vec<T>>;
typedef pair<ll, ll> P;
constexpr long long INF = 1LL << 60;
constexpr int INF_INT = 1 << 25;
constexpr long long MOD = (ll)1e9 + 7;
//constexpr long long MOD = 998244353LL;
using ld = long double;
static const ld pi = 3.141592653589793L;
typedef vector<ll> Array;
typedef vector<Array> Matrix;

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

struct Edge {
    ll to, rev;
    long double cap;
    Edge(ll _to, long double _cap, ll _rev) {
        to = _to;
        cap = _cap;
        rev = _rev;
    }
};
using Edges = vector<Edge>;
using Graph = vector<Edges>;

void add_edge(Graph &G, ll from, ll to, long double cap, bool revFlag,
              long double revCap) {
    G[from].push_back(Edge(to, cap, (ll)G[to].size()));
    if(revFlag)
        G[to].push_back(Edge(from, revCap, (ll)G[from].size() - 1));
}

void solve() {
    ll n;
    cin >> n;
    Graph g(n);
    REP(i, n) {
        ll u, k;
        cin >> u >> k;
        u--;
        REP(j, k) {
            ll v;
            cin >> v;
            v--;
            add_edge(g, u, v, 1, false, 1);
        }
    }

    Array d(n, 0);
    Array f(n, 0);
    int id = 1;
    auto dfs = [&](auto &&self, int v) -> void {
        d[v] = id;
        id++;
        for(auto e : g[v]) {
            if(d[e.to])
                continue;
            self(self, e.to);
        }
        f[v] = id;
        id++;
    };
    REP(i, n) {
        if(d[i])
            continue;
        dfs(dfs, i);
    }
    REP(i, n) {
        cout << i + 1 << " " << d[i] << " " << f[i] << en;
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    solve();

    /*
    ll t;
    cin >> t;
    REP(i, t) { solve();}
    */

    return 0;
}

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

int N;
const int maxn = 105;
const int WHITE = 0;
const int BLACK = 2;
int G[maxn][maxn];
vector<int> color;
vector<int> startTime;
vector<int> endTime;
vector<int> nt;

int getNext(int u){
    int res = -1;
    for(int i = nt[u];i<N;i++){
        if(G[u][i] && color[i]==WHITE){
            res = i;
            nt[u] = i;
            break;
        }
    }
    return res;
}

void DFS(int u,int &time){
    if(color[u]!=WHITE) return;
    stack<int> nodeStack;
    nodeStack.push(u);
    startTime[u] = time++;
    while(!nodeStack.empty()){
        int u = nodeStack.top();
        //if(color[u]!=WHITE) continue;
        color[u] = BLACK;

        int v = getNext(u);
        if(v!=-1){
            startTime[v] = time++;
            nodeStack.push(v);
            continue;
        }
        else{
            endTime[u] = time++;
            nodeStack.pop();
        }
    }
}

int main(){
    //freopen("data.txt","r",stdin);
    memset(G,0,sizeof(G));
    cin >> N;
    color.resize(N,WHITE);
    startTime.resize(N,0);
    endTime.resize(N,0);
    nt.resize(N,0);
    int u,k;
    for(int i = 0;i<N;i++){
        scanf("%d %d",&u,&k);
        u--;
        for(int j = 0;j<k;j++){
            int v;
            scanf("%d",&v);
            v--;
            G[u][v] = 1;
        }
    }
    int time = 1;
    for(int i = 0;i<N;i++) if(color[i]==WHITE) DFS(i,time);
    for(int u = 0;u<N;u++){
        printf("%d %d %d\n",u+1,startTime[u],endTime[u]);
    }
    return 0;
}