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+1)
	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++: // C++ 14
#include <iostream>
#include <vector>
#include <array>
#include <list>
#include <algorithm>
#include <queue>
#include <stack>
#include <math.h>

#define ll long long
#define Int int
#define INTMAX (1 << 21)
#define loop(x, start, end) for(Int x = start; x < end; x++)
#define loopdown(x, start, end) for(Int x = start; x > end; x--)

using namespace std;

#define MAX 100


void dfs(vector<Int> vs[], Int n) {
    Int t = 0;
    bool visited[n];
    Int ds[n];
    Int fs[n];
    
    loop(i,0,n) {
        visited[i] = false;
        ds[i] = fs[i] = 0;
    }
    
    stack<Int> S;
    loop(i,0,n) {
        if (visited[i]) continue;
        
        S.push(i);
        visited[i] = true;
        ds[i] = ++t;
    
loop:
        while (!S.empty()) {
            Int i = S.top();
            for (auto c: vs[i]) {
                if (visited[c]) continue;
                S.push(c);
                visited[c] = true;
                ds[c] = ++t;
                goto loop;
            }
            
            S.pop();
            fs[i] = ++t;
        }
    }
    
    loop(i,0,n) cout << i+1 << " " << ds[i] << " " << fs[i] << endl;
}


int main(void){
    Int n, x, cc, c;
    cin >> n;
    vector<Int> vs[n];
    loop(i,0,n) {
        cin >> x >> cc;
        loop(j,0,cc) {
            cin >> c;
            vs[x-1].push_back(c-1);
        }
        
    }
    dfs(vs, n);
}

C++: #include <iostream>


int D[100];
int F[100];
int V[100][100];

int cnt = 0;
int n;

void dfs(int r) {
    D[r] = ++cnt;
    for (int i = 0; i < n; i++) {
        if ((V[r][i] == 1) && (D[i] == 0)) {
            dfs(i);
        }
    }
    F[r] = ++cnt;
}

int main() {
    std::cin >> n;
    for (int i = 0; i < n; i++) {
        int id, e_num;
        std::cin >> id >> e_num;
        for (int j = 0; j < e_num; j++) {
            int t;
            std::cin >> t;
            V[id - 1][t - 1] = 1;
        }
    }

    for (int i = 0; i < n; i++) {
        if (!D[i]) dfs(i);
    }

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

C++: #include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#define WHITE 0
#define GRAY 1
#define BLACK 2
//ios::sync_with_stdio(false);
typedef long long LL;
using namespace std;
const int MAXN = 110;
int n, mapp[MAXN][MAXN], color[MAXN], d[MAXN], f[MAXN], tt;

void dfs_visit(int u) {
	color[u] = GRAY;
	d[u] = ++tt;
	for(int i = 0; i < n; i++) {
		if(mapp[u][i] == 1 && color[i] == WHITE) {
			dfs_visit(i);
		}
	}
	color[u] = BLACK;
	f[u] = ++tt;
}

void dfs() {
	tt = 0;
	memset(color, 0, sizeof(color));
	for(int i = 0; i < n; i++) {
		if(color[i] == WHITE) {
			dfs_visit(i);
		}
	}
	for(int i = 0; i < n; i++) {
		printf("%d %d %d\n", i+1, d[i], f[i]);
	}
}

int main() {
	int u, v, k;	
	cin >> n;
	memset(mapp, 0, sizeof(mapp));
	for(int i = 0; i < n; i++) {
		cin >> u >> k;
		u--;
		while(k--) {
			cin >> v;
			v--;
			mapp[u][v] = 1;
		}
	}
	dfs();
	return 0;
}

C++: #define _CRT_SECURE_NO_WARNINGS
#define MAX 2000000000
#include <iostream>
#include <algorithm>
#include <stack>
using namespace std ;

int d[102] = { 0 }, f[102] = {0};
int M[102][102];

int main() {
	stack<int> stk;
	int n;
	cin >> n;
	for (int i = 0;i < n;i++) {
		int k,l,m;
		cin >> m;
		cin >> k;
		for (int j = 0;j < k;j++) {
			cin >> l;
			M[m][l] = 1;
		}
	}
    
	stk.push(1);

    int i = 1,time=1,count=0;
    d[1]=1;
	while (count<n) {
		if (M[stk.top()][i]==1 && d[i]==0) {
			stk.push(i);
			d[stk.top()] = ++time;
			i=1;
		}
		else {
			i++;
			if (i > n) {
				f[stk.top()] = ++time;
				count++;
				stk.pop();
				i=1;
			}
		}
		if(stk.empty()){
		    for(int j=1;j<=n;j++)
		        if(d[j]==0){
		        stk.push(j);
		        d[stk.top()]=++time;
		        i=1;
		        break;
		    }
		}
	}
    
	for (int i = 1;i <= n;i++) {
		cout << i << " " << d[i] << " " << f[i] << endl;
	}
  
}

C++: #include<iostream>
#include<cstdio>
#include<cstring>
#include<stack>
#define white 0
#define grey 1
#define black -1
using namespace std;

int a[110][110],n;
int color[110];
int t;
int ts[110],te[110];
int nt[110];

void dfsinit()
{
    for(int i=1;i<=110;i++)
        {
            color[i]=white;
            nt[i]=0;
        }
}

int next(int i)
{
    for(int j=nt[i];j<=n;j++)
    {
        nt[i]=j+1;
        if(a[i][j]) return j;
    }
    return -1;
}

void dfsvisit(int u)
{
    for(int i=1;i<=n;i++)
        nt[i]=0;
    stack<int>s;
    s.push(u);
    ts[u]=++t;
    color[u]=grey;
    while(!s.empty())
    {
       int r=s.top();
       int v=next(r);
       if(v!=-1)
       {
          if(color[v]==white)
          {
              color[v]=grey;
              ts[v]=++t;
              s.push(v);
          }
       }
       else
       {
           color[r]=black;
           te[r]=++t;
           s.pop();
       }
    }
}

void dfs()
{
    dfsinit();

    for(int i=1;i<=n;i++)
    {
        if(color[i]==white)
        {
            dfsvisit(i);
        }
    }
}

int main()
{
   int key,d,x;
   t=0;
   memset(a,0,sizeof(a));
   scanf("%d",&n);
   for(int i=1;i<=n;i++)
   {
       scanf("%d%d",&key,&d);
       for(int j=1;j<=d;j++)
       {
        scanf("%d",&x);
        a[key][x]=1;
       }
   }

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