Go: package main

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

/***************************************************************
stackによる深さ優先探索を実装する。
***************************************************************/

const (
	N     = 100
	WHITE = 0
	GRAY  = 1
	BLACK = 2
)

var (
	n            int
	Adj          [N][N]int
	statusColor  [N]int
	discoverTime [N]int
	finishTime   [N]int
	clock        int
	nt           [N]int
)

/***************************************************************
Stackの定義:
- field
	container: ノードの格納されたスライス
	sp: スタックポインタ
- method
	size(): スタックに積まれているノードの個数を返す
	top(): スタックの一番上に積まれているノードを返す
	isEmpty(): スタックが空かどうかを返す
	pop(): スタックの要素をポップし削除する
	push(): スタックに要素を積む
***************************************************************/

type Stack struct {
	container []int
	sp        int
}

func (s *Stack) size() int {
	return len(s.container)
}

func (s *Stack) top() int {
	return s.container[s.sp]
}

func (s *Stack) isEmpty() bool {
	return s.sp == 0
}

func (s *Stack) pop() int {
	_pop := func() {
		s.container = s.container[:len(s.container)-1]
	}
	defer _pop()
	if s.isEmpty() {
		panic("There is no elements in stack!")
	}
	s.sp--
	return s.container[s.sp]
}

func (s *Stack) push(n int) {
	s.sp++
	s.container[s.sp] = n
}

func next(u int) int {
	for v := nt[u]; v < n; v++ {
		nt[u] = v + 1
		if Adj[u][v] == 1 {
			return v
		}
	}
	return -1
}

func _DFS(target int) {
	for i := 0; i < n; i++ {
		nt[i] = 0
	}
	stack := new(Stack)
	stack.container = make([]int, N)
	stack.push(target)
	statusColor[target] = GRAY
	clock++
	discoverTime[target] = clock
	for !stack.isEmpty() {
		u := stack.top()
		v := next(u)
		if v != -1 {
			if statusColor[v] == WHITE {
				statusColor[v] = GRAY
				clock++
				discoverTime[v] = clock
				stack.push(v)
			}
		} else {
			stack.pop()
			statusColor[u] = BLACK
			clock++
			finishTime[u] = clock
		}
	}
}

func DFS() {
	for i := 0; i < n; i++ {
		statusColor[i] = WHITE
		nt[i] = 0
	}
	clock = 0
	for i := 0; i < n; i++ {
		if statusColor[i] == WHITE {
			_DFS(i)
		}
	}
	for i := 0; i < n; i++ {
		fmt.Printf("%d %d %d\n", i+1, discoverTime[i], finishTime[i])
	}
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	scanner.Scan()
	n, _ = strconv.Atoi(scanner.Text())
	for i := 0; i < n; i++ {
		for j := 0; j < n; j++ {
			Adj[i][j] = 0
		}
	}
	for i := 0; i < n; i++ {
		scanner.Scan()
		u, _ := strconv.Atoi(scanner.Text())
		scanner.Scan()
		k, _ := strconv.Atoi(scanner.Text())
		u--
		for j := 0; j < k; j++ {
			scanner.Scan()
			v, _ := strconv.Atoi(scanner.Text())
			v--
			Adj[u][v] = 1
		}
	}

	DFS()
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(ll i = 0, i##_len = (n); i < i##_len; i++)
#define reps(i, s, n) for(ll i = (s), i##_len = (n); i < i##_len; i++)
#define rrep(i, n) for(ll i = (n) - 1; i >= 0; i--)
#define rreps(i, e, n) for(ll i = (n) - 1; i >= (e); i--)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())
#define len(x) ((ll)(x).length())

ll n, t = 0;
vector<vector<ll>> g;
vector<ll> d, f;

void dfs(ll v, ll p = -1) {
    if (d[v] != -1) return;
    t++;
    d[v] = t;
    rep(i, sz(g[v])) {
        if (g[v][i] == p) continue;
        dfs(g[v][i], v);
    }
    f[v] = t;
    t++;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    // ifstream in("input.txt");
    // cin.rdbuf(in.rdbuf());
    cin >> n;
    g.resize(n);
    rep(i, n) {
        ll u, k;
        cin >> u >> k;
        u--;
        rep(j, k) {
            ll v;
            cin >> v;
            v--;
            g[u].push_back(v);
        }
    }
    rep(i, n) sort(all(g[i]));
    d.resize(n, -1);
    f.resize(n, -1);
    rep(i, n) {
        if (d[i] == -1) dfs(i);
    }
    rep(i, n) {
        printf("%lld %lld %lld\n", i + 1, d[i], f[i] + 1);
    }
    return 0;
}

C++: #if 0
????????£?????????????´??????????
?????°?????¨??????dfs??????????????????????°??????§?????????
#endif

#include <iostream>
#include <vector>
using namespace std;
vector<int> E[101];
bool visited[101];
int in[101];
int out[101];
int count=0;
int nv(int n)
{
    int i=1;
    for(i=1;i<=n;i++)
    {
        if ( visited[i]==false )
            return i;
    }
    if (i>n) return 0;
}

void dfs(int n)
{
    visited[n]=true;
    in[n]=++count;
    for(vector<int>::iterator it=E[n].begin();it!=E[n].end();++it)
    {
        int now=*it;
        if(visited[now]==false)
            dfs(now);
    }
    out[n]=++count;
}

int main()
{
    int n;
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        int e,n0;
        cin>>e>>n0;
        for(int j=0;j<n0;j++)
        {
            int t;
            cin>>t;
            E[e].push_back(t);
        }
        visited[i]=false;
        in[i]=out[i]=0;
    }

    int now=nv(n);
    while(now!=0)
    {
        dfs(now);
        now=nv(n);
    }


/*  for(int i=1;i<=n;i++)
    {
        for(vector<int>::iterator it=E[i].begin();it!=E[i].end();++it)
            cout<<*it<<" ";
        cout<<endl;
    }
*/
    for(int i=1;i<=n;i++)
        cout<<i<<" "<<in[i]<<" "<<out[i]<<endl;
    return 0;



}

C++: #include <iostream>

using namespace std;

	int TIME = 0;
	int d[101];
	int f[101];
	int num;
	int graph[101][101] = {0};

void dfs(int x){
	TIME++;
	d[x] = TIME;

	for(int i=1;i<=num;i++){
		if(graph[x][i] == 1 && d[i]==0){
			dfs(i);
		}
	}
	f[x] = ++TIME;
}

int main(){
	int hon;
	int eda;
	int ver;

	cin>>num;
	for(int i=0;i<num;i++){
		cin>>eda;
		cin>>hon;
		for(int j=0;j<hon;j++){
			cin>>ver;
			graph[eda][ver]++;
		}
	}

	dfs(1);

	for(int i=1;i<=num;i++){
		cout<<i<<" "<<d[i]<<" "<<f[i]<<endl;
	}

	return 0;
}

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

int n;
vector<vector<int> > A;
vector<vector<int> > T;
int time = 0;

void dfs(int cur){ // cur????¨????
    // cur ????¨??????????????¨????
    time += 1;
    T[cur][0] = time;
    // ???????¢??????¨??¨???
    cerr << "visiting " << cur << " " << time << endl;

    for(int dst = 0; dst < n; ++dst){ // ??¨???????????? dst ????????????
        if(A[cur][dst] == 1 && T[dst][0] == -1){ // cur??????dst??????????????????,dst???????¨??????????
            dfs(dst);
        }
    }
    // cur ????¨????????????????????¨????
    time += 1;
    T[cur][1] = time;
    // ??¢??°?????????????????????????????? (?????¢??°)
    return; // ?????\???
}

int main(){
    cin >> n;
    vector<vector<int> > A(n, vector<int>(n, 0));
    vector<vector<int> > T(n, vector<int>(2, -1));
    for(int i=0; i<n; ++i){
        int k;
        cin >> k;
        // 1~n???index?????¨????????????????????????????????????1????????????0~n-1????????????
        k -= 1;
        int u;
        cin >> u;
        for(int j=0; j<u; ++j){
            int v;
            cin >> v;
            v -= 1;
            A[k][v] = 1;
        }
    }
    for(int i=0; i<n; ++i){
        if(T[i][0] == -1){
          dfs(i);
        }
    }
    for(int i=0; i<n; ++i){
        cout << i+1 << T[i][0] << T[i][1] << endl;
    }
}

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

const int maxn = 100;
vector<int> G[maxn + 5];
//int book[maxn + 5][maxn + 5];
int n;
int d[maxn + 5];
int f[maxn + 5];
int time = 0;


void dfs(int vertex) {
    d[vertex] = ++time;

    int len = G[vertex].size();
    for(int i = 0; i < len; i++) {
        if(!d[G[vertex][i]]) dfs(G[vertex][i]);
    }

    f[vertex] = ++time;
}

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

    for(int i = 1; i <= n; i++) {
        int num;
        scanf("%d", &num);
        int count;
        scanf("%d", &count);


        while(count--) {
            int temp; scanf("%d", &temp);
            G[num].push_back(temp);
        }
    }
    for(int i = 1; i <= n; i++) {
        if(!d[i]) dfs(i);
    }

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