Go: package main

import "fmt"

type node struct {
	id, d, v int
	adj      []node
}

var n int
var seen []bool
var graph []node

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func dfs(v, t int) int {
	// fmt.Printf("dfs(v %d, t %d) en:\n", v, t)
	seen[v] = true
	graph[v].v = t
	tt := t
	for _, vv := range graph[v].adj {
		if !seen[vv.id] {
			tt = max(tt, dfs(vv.id, tt+1))
		}
	}
	graph[v].d = tt + 1
	// fmt.Printf("dfs(v %d, t %d) ex: d %d\n", v, t, graph[v].d)
	return graph[v].d
}

func main() {
	fmt.Scan(&n)
	graph = make([]node, n+1)
	for i := 1; i <= n; i++ {
		var u, k, v int
		fmt.Scan(&u, &k)
		graph[u].id = u
		// 頂点uはk個の隣接頂点を持っている
		for j := 0; j < k; j++ {
			fmt.Scan(&v)
			var t node
			t.id = v
			graph[u].adj = append(graph[u].adj, t)
		}
	}
	// fmt.Println("n", n, "graph", graph)
	seen = make([]bool, n+1)
	// t := dfs(1, 1)
	v, t := 1, 1
	done := false
	for !done {
		tt := dfs(v, t)
		done = true
		for i := range seen {
			if !seen[i] {
				done = false
				v = graph[i].id
				t = tt
				break
			}
		}
	}
	for i := 1; i <= n; i++ {
		fmt.Printf("%d %d %d\n", i, graph[i].v, graph[i].d)
	}
}

C++: #include <bits/stdc++.h>
#define REP(i,n) for (int i = 0; i <(n); ++i)
#define ALL(v) v.begin(), v.end()
using namespace std;
//using ll = long long;
//using P = pair<int,int>;
//static const double PI = acos(-1);


//---------------------------//
//DFS 再帰関数を利用


static const int N     = 100;
static const int WHITE = 0;
static const int GRAY  = 1;
static const int BLACK = 2;

//隣接行列
int n, M[N][N];
int color[N], d[N], f[N], tt;

void dfs_visit(int u){
  //cout << "u: " << u << endl; //来訪地点のチェック
  color[u] = GRAY;
  d[u] = ++tt;  //最初に訪れたときの処理
  REP(v,n){
    if(M[u][v] == 0) continue;
    //cout << "v: " << v << endl; // 次に向かう点をチェック
    if(color[v] == WHITE) {
      dfs_visit(v); //再帰
    }
  }
  color[u] = BLACK;
  f[u] = ++tt;  //最後に訪れたときの処理

}


void dfs(){
  //int u;
  // 初期化
  REP(u,n) color[u] = WHITE;
  tt = 0;
  //
  REP(u,n) {
    if( color[u] == WHITE) dfs_visit(u); //再帰関数に
  }
  REP(u,n){
    cout << u+1 << " " << d[u] << " " << f[u] << endl;
    //cout << color[u] << endl;
  }


}


int main(){
  int u,k,v;
  cin >> n;
  //隣接行列の初期化
  REP(i,n) REP(j,n) M[i][j] = 0;


  //隣接行列の作製
  REP(i,n){
    cin >> u >> k;
    --u;
    REP(j,k){
      cin >> v;
      --v;
      M[u][v] = 1;
    }

  }
  //dfs
  dfs();


  //隣接行列のoutput(確認用)
  //REP(i,n) {REP(j,n) cout << M[i][j];cout << endl;}



  return 0;
}

C++: #include<iostream>
#include<stack>
const int N = 100;
using namespace std;
int n,M[N][N];
int color[N],nt[N],d[N],f[N],start;
int next(int u){
	for(int i=nt[u];i<n;i++){
        nt[u] = i+ 1;
        if(M[u][i]) return i;
    }
	return -1;
}
void dfs_visit(int u){
    for(int i=0;i<n;i++) nt[i] = 0;
    stack<int> s;
	s.push(u);
	color[u] = 1;
	d[u] = ++start;
	while(!s.empty()){
		int x = s.top();
		int v = next(x);
		if(v!=-1){
			if(!color[v]){
				s.push(v);
				d[v] = ++start;
				color[v] = 1;
			}
		}else{
			s.pop();
            color[x] = 1;
			f[x] = ++start;
		}
	}
}
void dfs(){
	start = 0;
	for(int i=0;i<n;i++)
            if(!color[i])
	            dfs_visit(i);
	for(int i=0;i<n;i++)
		printf("%d %d %d\n",i+1,d[i],f[i]);
}
int main(){
	scanf("%d",&n);
	for(int i=0;i<n;i++){
		int u,k,v;
		scanf("%d%d",&u,&k);
		while(k--){
			scanf("%d",&v);
			M[u-1][v-1] = 1;
		}
	}
	dfs();
	return 0;
}

C++: #include <stdio.h>
#define REP(i,n) for(int i=0;i<n;i++)
#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2
int n,M[N][N]={0};
int color[N]={WHITE},D[N],F[N],tt=0;
void DFS_VISIT(int u){
  int v;
  color[u]=GRAY;
  D[u]=++tt;
  REP(v,n){
    if(M[u][v]==0) continue;
    if(color[v]==WHITE) DFS_VISIT(v);
  }
  color[u]=BLACK;
  F[u]=++tt;
}
void DFS(){
  int u;
  REP(u,n) if(color[u]==WHITE) DFS_VISIT(u);
  REP(u,n) printf("%d %d %d\n",u+1,D[u],F[u]);
}
int main(){
  int u,v,k;
  scanf("%d",&n);
  REP(i,n){
    scanf("%d %d",&u,&k);
    u--;
    REP(j,k){
      scanf("%d",&v);
      M[u][--v]=1;
    }
  }
  DFS();
  return 0;
}

C++: #include <iostream>
//#include <iomanip>
//#include <string>
#include <vector>
#include <algorithm>
//#include <utility>
//#include <set>
//#include <map>
//#include <queue>
//#include <deque>
//#include <bitset>
//#include <math.h>
using namespace std ;
using ll = long long ;
//using ld = long double ;
using vll = vector<ll> ;
using vvll = vector<vll> ;
//using vc = vector<char> ;
//using vvc = vector<vc> ;
//using vb = vector<bool> ;
//using vvb = vector<vb> ;
//using pll = pair<ll,ll> ;
#define all(v) v.begin(),v.end()
//ll mod = 1000000007 ;
//long double pie = acos(-1) ;
//ll INF = 1000000000000 ;

//void yorn(bool a){if(a) cout << "Yes" << endl ; else cout << "No" << endl ;}
//void YorN(bool a){if(a) cout << "YES" << endl ; else cout << "NO" << endl ;}
//ll gcd(long long a,long long b){if(b==0) return a ; return gcd(b,a%b) ;}
//ll lcm(long long a,long long b){return a/gcd(a,b)*b ;}
//ll sa(long long a,long long b){if(a>b) return a-b ; return b-a ;}
//void fix_cout(){cout << fixed << setprecision(20) ;}
//void chmin(ll &a,ll b){if(a>b) a = b ;}

ll cnt = 1 ;

void DFS(vvll &g,vvll &ans,ll p){
	if(ans.at(p).at(0)!=-1) return ;
	ans.at(p).at(0) = cnt ;
	cnt++ ;
	for(int i=0;i<g.at(p).size();i++){
		DFS(g,ans,g.at(p).at(i)) ;
	}
	ans.at(p).at(1) = cnt ;
	cnt++ ;
}

int main(){
	ll n ; cin >> n ;
	vvll g(n,vll(0)) ;
	for(int i=0;i<n;i++){
		ll a,b ;
		cin >> a >> b ;
		vll c(b) ;
		for(int j=0;j<b;j++) cin >> c.at(j) ;
		sort(all(c)) ;
		for(int j=0;j<b;j++) g.at(i).emplace_back(c.at(j)-1) ;
	}
	vvll ans(n,vll(2,-1)) ;
	for(int i=0;i<n;i++){
		if(ans.at(i).at(0)==-1) DFS(g,ans,i) ;
	}
	for(int i=0;i<n;i++) cout << i+1 << " " << ans.at(i).at(0) << " " << ans.at(i).at(1) << "\n" ;
}

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

vector<int> G[100];
pair<int, int> T[100];
const int Inf = 10000*100000+100;
int timer = 1;

int main() {
  void dfs(int cur);
  int n;
  cin >> n;
  for (int i = 0; i < n; i++)
  {
    int u, k;
    cin >> u >> k;
    for (int l = 0; l < k; l++) {
      int v;
      cin >> v;
      G[i].push_back(v - 1);
    }
    T[i] = make_pair(Inf, Inf);
  }
  for (int i = 0; i < n; i++) {
    if (T[i].first == Inf) {
      dfs(i);
    }
  }
  for (int i = 0; i < n; i++)
  {
    cout << i + 1 << " " << T[i].first << " " << T[i].second << endl;
  }
}

void dfs(int cur) { // cur を訪問
  // cur の訪問時刻を記録
  T[cur].first = timer;
  timer += 1;
  // 動作確認用表示
  for (int dst : G[cur]) { // 全ての節点 dst について
    if (T[dst].first == Inf)
    { // cur から dst に辺があり，dst を未訪問なら
      dfs(dst);
    }
  }
  T[cur].second = timer;
  timer += 1;
}

C++: #include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>
#include<stack>
#include<queue>
#include<vector>
#include<algorithm>
#include<string>
#include<iostream>
using namespace std;
static const int N=105;
int M[N+1][N+1];
void graph(int n){
    for(int i=1;i<=n;i++){
        int garbage;cin>>garbage;
        int k;cin>>k;
        for(int j=1;j<=k;j++){
            int l;cin>>l;
            M[i][l]=1;
        }
    }
}
int d[N],f[N],t=1,n;
stack <int>S;
void dfs(){
    S.push(1);
    d[1]=t;
    while(S.empty()!=true){
        int flag=0,i=1;
        while(flag==0 && i<=n){
            if(M[S.top()][i]==0){
                i++;
            }else{
                    flag++;
                for(int z=1;z<=n;z++) M[z][i]=0;
                
            }
        }
        t++;
        if(i>=n+1){
            f[S.top()]=t;
            S.pop();
        }else{
            S.push(i);
            d[i]=t;
        }
    }
}

int main(){
    cin>>n;
    graph(n);
    dfs();
    for(int i=1;i<=n;i++){
        cout<<i<<" "<<d[i]<<" "<<f[i]<<endl;
    }
    
    return 0;
}