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>
using namespace std;
int t = 1;
int d[100], f[100];
int a[100][100];
int N;
void dfs(int cur) {
 d[cur] = t;
 t++;
 for (int i=0; i<N; i++) {
  if (a[cur][i] == 1 && d[i] == 0) {
   dfs(i);
  }
 }
 f[cur] = t;
 t++;
}

int main() {
 cin >> N;
 for (int i=0; i<N; i++) {
  for (int j=0; j<N; j++) {
   a[i][j] = 0;
  }
  d[i] = 0;
  f[i] = 0;
 }
 for (int i=0; i<N; i++) {
  int u, k;
  cin >> u >> k;
  for (int j=0; j<k; j++) {
   int v;
   cin >> v;
   a[u-1][v-1] = 1;
  }
 }
 for (int i=0; i<N; i++) {
  if (d[i] == 0) { dfs(i); }
 }
 for (int i=0; i<N; i++) {
  cout << i+1 << " " << d[i] << " " << f[i] << endl;
 }
}

C++: #include <iostream>
#include <stack>

using namespace std;

static const int N = 100;
static const int WHITE = 0;//?????¢?´¢
static const int GRAY = 1;//??¢?´¢???
static const int BLACK = 2;//??¢?´¢??????

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

/**
  *??£??\?????¢???
  */
int next(int u) {
  for(int v = nt[u]; v < n; v++) {
    nt[u] = v + 1;
    if(M[u][v]) return v;
  }
  return -1;
}

/**
  *??±???????????¢?´¢???????????¨???
  */
void dfs_visit(int r) {
  for(int i = 0; i < n; i++) nt[i] = 0;

  stack<int> S;
  S.push(r);
  color[r] = GRAY;
  d[r] = ++tt;

  /*
    ??£?????°???????????????????????¨?????¢?´¢?????????????????§??°?????????
  */
  while(!S.empty()) {
    int u = S.top();
    int v = next(u);
    if(v != -1) {
      //??¢?´¢??????????????????????????£?????¢?´¢
      if(color[v] == WHITE) {
        color[v] = GRAY;
        d[v] = ++tt;
        S.push(v);
      }
    }
    else {
      //??£???????????¨?????¢?´¢?????????
      S.pop();
      color[u] = BLACK;
      f[u] = ++tt;
    }
  }
}

/**
  *?????£?????°???????????¢?´¢??????????????????
  **/
void dfs() {
  //init
  for(int i = 0; i < n; i++) {
    color[i] = WHITE;
    nt[i] = 0;
  }
  tt = 0;


  for(int u = 0; u < n; u++) {
    //?????¢?´¢????????????????±??????¢?´¢
    if(color[u] == WHITE ) dfs_visit(u);
  }
  for(int i = 0; i < n; i++) {
    cout << i + 1 << " " << d[i] << " " <<f[i] << endl;
  }
}


int main(void) {
  int u, k, v;
  cin >> n;
  //init
  for(int i = 0; i < n; i++) {
    for(int j = 0; j < n; j++) {
      M[i][j] = 0;
    }
  }


  //??£??\???????????¨??????0-origin?????£??\???????????????
  for(int i = 0; i < n; i++) {
    cin >> u >> k;
    u--;
    for(int j = 0; j < k; j++) {
      cin >> v;
      v--;
      M[u][v] = 1;
    }
  }

  dfs();

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0; i<(n); i++)
using ll = long long;
using P = pair<int, int>;
#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;

// 再帰関数による深さ優先探索

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<iostream>
#include<vector>
#include<queue>
#include"print_vec.h"

using namespace std;

vector<vector<int>> adjacent;
vector<pair<int, int>> ans;
vector<bool>checked;

//?????????is????????????
int dfs(int now,int time = 1) {
	cout << now << endl;
	ans[now].first = time;
	checked[now] = true;
	for (int i = 0; i < adjacent[now].size(); i++) {
		if (!checked[adjacent[now][i]]) {
			time = dfs(adjacent[now][i], time + 1);
		}
	}
	ans[now].second = time+1;
	return time + 1;
}

int main() {
	int n;
	cin >> n;
	adjacent = vector<vector<int>>(n);
	checked = vector<bool>(n, false);
	ans.resize(n);

	for (int i = 0; i < n; i++) {
		int u, k;
		cin >> u >> k;
		for (int j = 0; j < k; j++) {
			int v;
			cin >> v;
			adjacent[u - 1].push_back(v-1);
		}
	}

	dfs(0, 1);
	
	for (int i = 0; i < n; i++) {
		cout << i + 1 << " " << ans[i].first << " " << ans[i].second << endl;
	}

}