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 <iostream>
#include <vector>
#include <numeric>

const int MAXINT = std::numeric_limits<int>::max();

// typedef std::vector<std::vector<int> > mat_int;
// typedef std::vector<std::vector<bool> > mat_bool;

void dfs(std::vector<std::vector<int> >& adj_list, std::vector<int>& d, std::vector<int>& f, int& time, int root = 0 ){
  if(d[root] > time){
    d[root] = time;
    for(int const& v: adj_list[root]){
      time++;
      dfs(adj_list, d, f, time, v);
    }
    time++;
    f[root] = time;
  }

}


int main(int argc, char const *argv[]) {
  int n; // .. 100
  std::cin >> n;
  // mat_bool adj(n, std::vector<bool>(n));
  // mat_int d(n, std::vector<int>(n)), f(n, std::vector<int>(n));
  std::vector<std::vector<int> > adj_list(n);
  std::vector<int> d(n, MAXINT), f(n, MAXINT);

  for(int q=0; q<n; ++q){
    int i_plus_1, k;
    std::cin >> i_plus_1;
    std::cin >> k;
    for(int p=0; p<k; ++p){
      int j_plus_1;
      std::cin >> j_plus_1;
      // adj[i_plus_1-1][j_plus_1-1] = true;
      adj_list[i_plus_1 - 1].push_back(j_plus_1-1);
    }
  }

  int t = 1;
  dfs(adj_list, d, f, t);

  for(int i=0; i<n; ++i){
    std::cout << (i+1)
      << " " << d[i]
      << " " << f[i]
      << std::endl;

  }


  // for(auto it = adj_list.begin(); it != adj_list.end(); ++it){
  //   std::cout << ": ";
  //   for(auto jt = (*it).begin(); jt != (*it).end(); ++jt){
  //     std::cout << (*jt) << ' ';
  //   }
  //   std::cout << std::endl;
  // }

  return 0;
}

C++: #include <algorithm>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>

#define pb push_back
#define debug(x) cout<< #x <<": "<<x<<endl
#define debug2(x,y) cout<< #x <<": "<< x <<", "<< #y <<": "<< y <<endl

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<i_i, int> p_i;
typedef vector<int> vi;
typedef vector<vector<int> > vvi;
template<class T> using vv=vector<vector< T > >;

vi ts_d;
vi ts_f;

template<class T>
void dfs(int cur, int &time_visit, T graph) {
  // visiting cur
  time_visit += 1;
  ts_d[cur] = time_visit;
  for (auto dst : graph[cur]) {
    if (ts_d[dst] == 0) {
      dfs(dst, time_visit, graph);
    }
  }
  time_visit += 1;
  ts_f[cur] = time_visit;
}

int main() {
  int time = 0;
  int n;
  cin >> n;
  ts_d.reserve(n);
  ts_f.reserve(n);
  ts_d.assign(1, 0);
  vector<set<int> > graph(n, set<int>());

  for (int i = 0; i < n; ++i) {
    int num;
    cin >> num;
    num -= 1;
    int out;
    cin >> out;
    for (int j = 0; j < out; ++j) {
      int tmp;
      cin >> tmp;
      tmp -= 1;
      graph[i].insert(tmp);
    }
  }

  dfs(0, time, graph);

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

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i, a) for(int i=0; i<(int)(a); i++)
vector<vector<int>> a;
vector<int> b;
vector<int> s;
vector<int> t;
int c = 1;

void dfs(int x)
{
  if (b[x]==1) return;
  b[x] = 1;
  s[x] = c; c++;
  for (auto v:a[x]) {
    dfs(v);
  }
  t[x] = c; c++;
}

int main()
{
  int n; cin>>n;
  a.resize(n);
  b.resize(n); rep(i, n) b[i]=0;
  s.resize(n); rep(i, n) s[i]=0;
  t.resize(n); rep(i, n) t[i]=0;
  rep(i, n) {
    int u; cin>>u; u--;
    int k; cin>>k;
    rep(j, k) {
      int v; cin>>v; v--;
      a[u].push_back(v);
    }
  }
  rep(i, n) dfs(i);
  rep(i, n) printf("%d %d %d\n", i+1, s[i], t[i]);

  return 0;
}

C++: //#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define all(v) v.begin(), v.end()
using in = int64_t;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define REP(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
const double PI=3.14159265358979323846;
const in MOD = 1000000007;
const in INF=1<<30;
using P=pair<int,int>;
vector<int> dx={0,1,-1,0};
vector<int> dy={1,0,0,-1};

vector<vector<int>> a(0);
int g;
vector<int> s(0),t(0);
int cnt=1;

int dfs(int x){
    s[x]=cnt;
    cnt ++;
    for(auto y:a[x]){
        if(s[y]==-1){
            dfs(y);
        }
    }
    t[x]=cnt;
    cnt ++;
}

int main(){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cout << fixed << setprecision(10);
    cin>>g;
    a=vector<vector<int>>(g,vector<int>(0));
    int k,x;
    rep(i,g){
        cin>>k;
        cin>>k;
        rep(j,k){
            cin>>x;
            a[i].emplace_back(x-1);
        }
    }
    s.resize(g,-1);t.resize(g,-1);
    rep(i,g){
        if(s[i]==-1) dfs(i);
    }
    rep(i,g) cout<<i+1<<" "<<s[i]<<" "<<t[i]<<'\n';
}