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 <string>
#include <vector>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <limits>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <functional>
#include <iomanip>

using namespace std;

#ifdef LOCAL
#define eprintf(...) fprintf(stderr, __VA_ARGS__)
#else
#define eprintf(...) 42
#endif
using ll = long long;
using vll = std::vector<ll>;
using vvll = std::vector<vll>;
using vvvll = std::vector<vvll>;
#define reps(i, S, E) for (ll i = (S); i <= (E); i++)
#define rep(i, N) reps(i, 0, N-1)
#define deps(i, E, S) for (ll i = (E); i >= (S); i--)
#define dep(i, N) deps(i, N-1, 0)
const ll INF = 1LL << 60;
const int INF_INT = 1 << 30;

template<class T> inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; }return false; }
template<class T> inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; }return false; }
struct mll {
	static ll MOD;
	ll val;
	mll(ll v = 0) : val(v % MOD) { if (val < 0) val += MOD; }
	mll operator - () const { return -val; }
	mll operator + (const mll &b) const { return val + b.val; }
	mll operator - (const mll &b) const { return val - b.val; }
	mll operator * (const mll &b) const { return val * b.val; }
	mll operator / (const mll &b) const { return mll(*this) /= b; }
	mll operator + (ll b) const { return *this + mll(b); }
	mll operator - (ll b) const { return *this - mll(b); }
	mll operator * (ll b) const { return *this * mll(b); }
	friend mll operator + (ll a, const mll &b) { return b + a; }
	friend mll operator - (ll a, const mll &b) { return -b + a; }
	friend mll operator * (ll a, const mll &b) { return b * a; }
	mll &operator += (const mll &b) { val = (val + b.val) % MOD; return *this; }
	mll &operator -= (const mll &b) { val = (val + MOD - b.val) % MOD; return *this; }
	mll &operator *= (const mll &b) { val = (val*b.val) % MOD; return *this; }
	mll &operator /= (const mll &b) {
		ll c = b.val, d = MOD, u = 1, v = 0;
		while (d) {
			ll t = c / d;
			c -= t * d; swap(c, d);
			u -= t * v; swap(u, v);
		}
		val = val * u % MOD;
		if (val < 0) val += MOD;
		return *this;
	}
	mll &operator += (ll b) { return *this += mll(b); }
	mll &operator -= (ll b) { return *this -= mll(b); }
	mll &operator *= (ll b) { return *this *= mll(b); }
	mll &operator /= (ll b) { return *this /= mll(b); }
	bool operator == (const mll &b) { return val == b.val; }
	bool operator != (const mll &b) { return val != b.val; }
	bool operator == (ll b) { return *this == mll(b); }
	bool operator != (ll b) { return *this != mll(b); }
	friend bool operator == (ll a, const mll &b) { return mll(a) == b.val; }
	friend bool operator != (ll a, const mll &b) { return mll(a) != b.val; }
	friend ostream &operator << (ostream &os, const mll &a) { return os << a.val; }
	friend istream &operator >> (istream &is, mll &a) { return is >> a.val; }
	static mll Combination(ll a, ll b) {
		chmin(b, a - b);
		if (b < 0) return mll(0);
		mll c = 1;
		rep(i, b) c *= a - i;
		rep(i, b) c /= i + 1;
		return c;
	}
};
using vmll = std::vector<mll>;
using vvmll = std::vector<vmll>;
using vvvmll = std::vector<vvmll>;
using vvvvmll = std::vector<vvvmll>;

struct Fast {
	Fast() {
		cin.tie(0);
		ios::sync_with_stdio(false);
		cout << fixed << setprecision(std::numeric_limits<double>::max_digits10);
	}
} fast; //cin,cout高速化のおまじない＋桁数指定

ll mll::MOD = (ll)(1e9 + 7);// 998244353ll;


vvll g; //グラフ
vll d; //ノードを最初に発見した発見時刻
vll f; //ノードの隣接リストを調べ終えた完了時刻
ll now; //時刻

void DFS(ll node) {
	//nodeを起点とした探索
	for (auto next : g[node]) {
		if (d[next] > 0) {
			// 発見済み
			continue;
		}
		else {
			// 新発見
			now++;
			d[next] = now;
			DFS(next);
		}
	}

	//nodeを起点とした探索が完了
	now++;
	f[node] = now;
}

int main() {
	ll N;
	cin >> N;

	g.resize(N + 1);

	rep(i, N) {
		ll I;
		cin >> I;
		ll C;
		cin >> C;
		g[I].resize(C);
		rep(j, C) {
			ll V;
			cin >> V;
			g[I][j] = V;
		}
	}

	d.resize(N + 1, 0);
	f.resize(N + 1, 0);
	now = 0;
	ll startNodeIndex = 1; // 未探索のノードを探す際のインデックス

	while (startNodeIndex <= N) {
		// 新たな未発見ノードを選ぶ
		if (d[startNodeIndex] <= 0) {
			now++;
			d[startNodeIndex] = now;
			DFS(startNodeIndex);
		}
		startNodeIndex++;
	}

	reps(i, 1, N) {
		cout << i << " " << d[i] << " " << f[i] << endl;
	}

	return 0;
}

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

using namespace std;

vector<int> G[100];
int n;
int t;
int vn,un;
int s[100],f[100];
int inf = 1<<21;
int tim=1;

void dfs(int u){
    //cout << u << " " << s[u] << " " << f[u] << endl;
    s[u] = tim;
    tim++;
    for(int i=0;i<G[u].size();i++){
        int v = G[u][i];
        if(s[v] == inf){
            dfs(v);
        }
    }
    f[u] = tim;
    tim++;
}

int main(){
    cin >> n;
    for(int i=0;i<n;i++){
        cin >> vn >> un;
        vn--;
        for(int j=0;j<un;j++){
            cin >> t;
            t--;
            //cout << t << " " << vn << endl;
            G[vn].push_back(t);
        }
    }
    fill(s,s+n,inf);
    fill(f,f+n,inf);
    //cout << s[2] << " " << f[3] << endl;
    for(int i=0;i<n;i++){
        if(f[i] == inf) dfs(i);
    }
    for(int i=0;i<n;i++){
        cout << i+1 << " " << s[i] << " " << f[i] << endl;
    }
    return 0;

}