Go: package main

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

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	nVerts := scanInt(sc)
	graph := make([][]int, nVerts+1)

	for i := 0; i < nVerts; i++ {
		u := scanInt(sc)
		nDegrees := scanInt(sc)

		graph[u] = make([]int, nDegrees)
		for d := 0; d < nDegrees; d++ {
			graph[u][d] = scanInt(sc)
		}
	}

	starts := make([]int, nVerts+1)
	ends := make([]int, nVerts+1)
	time := 1

	var dfs func(u int)
	dfs = func(u int) {
		if starts[u] > 0 {
			return
		}

		starts[u] = time
		time += 1

		for _, v := range graph[u] {
			dfs(v)
		}

		ends[u] = time
		time += 1
	}

	for i := 1; i <= nVerts; i++ {
		dfs(i)
	}

	w := bufio.NewWriter(os.Stdout)
	for i := 1; i <= nVerts; i++ {
		fmt.Fprintf(w, "%d %d %d\n", i, starts[i], ends[i])
	}
	w.Flush()
}

func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	v, _ := strconv.Atoi(sc.Text())
	return v
}

C++: #include <iostream>
#include <iomanip> // << fixed << setprecision(xxx)
#include <algorithm> // do { } while ( next_permutation(A, A+xxx) ) ;
#include <vector>
#include <string> // to_string(nnn) // substr(m, n) // stoi(nnn)
#include <complex>
#include <tuple> // get<n>(xxx)
#include <queue>
#include <stack>
#include <map> // if (M.find(key) != M.end()) { }
#include <set> // S.insert(M);
// if (S.find(key) != S.end()) { }
// for (auto it=S.begin(); it != S.end(); it++) { }
// auto it = S.lower_bound(M);
#include <random> // random_device rd; mt19937 mt(rd());
#include <cctype>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib> // atoi(xxx)
using namespace std;

#define DEBUG 0 // change 0 -> 1 if we need debug.
// insert #if<tab> by my emacs. #if DEBUG == 1 ... #end

typedef long long ll;

// const int dx[4] = {1, 0, -1, 0};
// const int dy[4] = {0, 1, 0, -1};

// const int C = 1e6+10;
// const ll M = 1000000007;

class Edge {
public:
  int src, dst, cost;
  Edge(int s, int d, int c)
    : src(s), dst(d), cost(c) {}
  friend bool operator<(const Edge& x, const Edge& y) {
    return x.cost < y.cost;
  }
};

typedef Edge State;

class Graph {
public:
  int N;
  vector<Edge>* V;
  int* visited;
  int* from;
  int time;
  int* time_d;
  int* time_f;

  Graph(int n)
    : N(n), time(0) {
    V = new vector<Edge>[N];
    from = new int[N];
    time_d = new int[N];
    time_f = new int[N];
    visited = new int[N];
    fill(visited, visited+N, 0);
  }
  ~Graph() {
    delete[] V;
    delete[] from;
    delete[] time_d;
    delete[] time_f;
    delete[] visited;
  }

  void add_edge(int src, int dst, int cost = 1) {
    V[src].push_back(Edge(src, dst, cost));
  }

  void dfs(int start) {
    stack<State> S;
    S.push(State(-1, start, 0));
    while (!S.empty()) {
      State s = S.top();
      S.pop();
      if (visited[s.dst] == 0) {
        visited[s.dst] = 1;
        time_d[s.dst] = time++;
        from[s.dst] = s.src;
        S.push(s);
        for (auto x : V[s.dst]) {
          if (visited[x.dst] == 0) {
            S.push(State(s.dst, x.dst, s.cost + x.cost));
          }
        }
      } else if (visited[s.dst] == 1) {
        visited[s.dst] = 2;
        time_f[s.dst] = time++;
      }
    }
  }
};

int main () {
  int n;
  cin >> n;
  Graph graph(n);
  for (auto i = 0; i < graph.N; ++i) {
    int u, k;
    cin >> u >> k;
    --u;
    for (auto j = 0; j < k; ++j) {
      int v;
      cin >> v;
      --v;
      graph.add_edge(u, v);
    }
  }
  for (auto i = 0; i < graph.N; ++i) {
    sort(graph.V[i].begin(), graph.V[i].end());
    reverse(graph.V[i].begin(), graph.V[i].end());
  }
  while (true) {
    bool used = false;
    for (auto i = 0; i < graph.N; ++i) {
      if (graph.visited[i] == 0) {
        graph.dfs(i);
        used = true;
        break;
      }
    }
    if (!used) break;
  }
  for (auto i = 0; i < graph.N; ++i) {
    cout << i+1
         << " " << graph.time_d[i]+1
         << " " << graph.time_f[i]+1 << endl;
  }
}

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

int t = 0;
vector<int> edge[101];
bool back_edge[101];

pair<int, int> visit_time[101];

void dfs(int cur)
{
    t += 1;
    visit_time[cur].first = t;

    for (int i = 0; i < (int)edge[cur].size(); i++) // cur から行ける頂点について
    {
        if (back_edge[edge[cur][i]] == false)
        {
            back_edge[edge[cur][i]] = true;
            dfs(edge[cur][i]);
        }
    }

    t += 1;
    visit_time[cur].second = t;
}

int main()
{
    int n;
    cin >> n;

    for (int i = 0; i < n; i++)
    {
        int u, k;
        cin >> u >> k;
        back_edge[u] = false;
        for (int j = 0; j < k; j++)
        {
            int v;
            cin >> v;
            edge[u].push_back(v);
        }
    }

    for (int i = 1; i < n; i++)
        if (back_edge[i] == false)
        {
            back_edge[i] = true;
            dfs(i);
        }

    for (int i = 1; i <= n; i++)
    {
        cout << i
             << " " << visit_time[i].first
             << " " << visit_time[i].second << endl;
    }
}

C++: #include<stdio.h>
#include<iostream>
#define N 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

int n,M[N][N];
int color[N],d[N],f[N],tt;

void dfs_visit(int u){
    int v;
    color[u]=GRAY;
    d[u]=++tt; //最初の訪問
    for(v=0; v<n; v++){
        if(M[u][v]==0){ continue; }
        if(color[v]==WHITE){ dfs_visit(v); } 
    }
    color[u]=BLACK;
    f[u]=++tt;//訪問の完了
}

void dfs(){
    int u;
    //初期化
    for(u=0; u<n; u++){ 
        color[u]=WHITE; 
    }

    tt=0;

    for(u=0; u<n; u++){
        //未訪問のuを始点として深さ優先探索
        if(color[u]==WHITE){ dfs_visit(u); }
    }

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

int main(){
    int u,v,k,i,j;

    scanf("%d",&n);
    for(i=0; i<n; i++){
        for(j=0; j<n; j++){
            M[i][j]=0;
        }
    }

    for(i=0; i<n; i++){
        scanf("%d %d",&u,&k);
        u--;
        for(j=0; j<k; j++){
            scanf("%d",&v);
            v--;
            M[u][v]=1;
        }
    }

    dfs();

    return 0;
}

C++: #include <stdio.h>

int A[101][101];
int ans[101][3];
int an = 1;

int serch(int a[101][101], int  ni, int n){
  int  j;
  
  for(j=0; j<n; j++){
    if(A[ni][j] == 1){
      judge(j, 1);
      serch(A, j, n);
    }
  }
  judge(ni, 2);
}

int judge(int i, int j){
  if(ans[i][j] == 0){
    ans[i][j] = an;
    an++;
  }
}

int  main(){
  int i, j, k, n, x, y;
  
  scanf("%d", &n);
  
  for(i=0; i<n; i++){
    for(j=0; j<n; j++)
      A[i][j] = 0;
    ans[i][0] = i+1;
  }
  
  for(i=0; i<n; i++){
    scanf("%d %d", &x, &y);
    for(j=0; j<y; j++){
      scanf("%d", &k);
      A[i][k-1] = 1;
    }
  }
  
  judge(0, 1);
  
  for(i=0; i<n; i++){
    if(A[0][i] == 1){
      judge(i, 1);
      serch(A, i, n);
    }
  }
  judge(0, 2);
  
  for(i=0; i<n; i++){
    for(j=0; j<3; j++){
      if(j>0)
        printf(" ");
      printf("%d", ans[i][j]);
    }
    printf("\n");
  }
  
  return 0;
}

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

const int MAX_N = 100;
int to[MAX_N][MAX_N];
int ans[MAX_N][2];
bool visited[MAX_N];
int depth = 1;

void dfs(int x) {
  if (ans[x][0] == -1) ans[x][0] = depth++;
  for (int i=0; to[x][i] != -1 && !visited[to[x][i]]; i++) {
    dfs(to[x][i]);
  }
  if (ans[x][1] == -1) ans[x][1] = depth++;
}

int main() {
  int N;
  cin >> N;
  for (int i=0; i<N; i++) {
    for (int j=0; j<N; j++) {
      to[i][j] = -1;
    }
    ans[i][0] = ans[i][1] = -1;
    visited[i] = false;
  }
  for (int i=0; i<N; i++) {
    int tmp, n;
    cin >> tmp >> n;
    for (int j=0; j<n; j++) {
      int t;
      cin >> t; t--;
      to[i][j] = t;
    }
  }

  visited[0] = true;
  dfs(0);
  for (int i=0; i<N; i++) {
    cout << i+1 << " " << ans[i][0] << " " << ans[i][1] << endl;
  }
  return 0;
}