#define _CRT_SECURE_NO_WARNINGS
#pragma comment(linker, "/STACK:251700000")
#include <iostream>
#include <vector>
#include <set>
#include <string>
#include <algorithm>
#include <queue>
#include <cstdio>
#include <fstream>
#include <unordered_map>
#include <map>
#include <iterator>
#include <iomanip>
#include <stack>
#include <math.h>
#include <bitset>
#include <assert.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef unsigned long long ull;
typedef unsigned int ui;
typedef vector<int> vi;

#define TASK "magican"
#define mp make_pair
#define X first
#define Y second
#define all(a) (a).begin(), (a).end()
#define inb push_back
#define y1 lubluAU

const ll LINF = 9e18;
const long double eps = 1e-9;
const int INF = 2e9;

const int M = 2e5 + 5;

int n, a[M], us[M], x, was[M], dp[M][2];
vi pr[M];
pii vv[M];
int an1, an2;

void dfs(int v)
{
	us[v] = 1;
	if (us[a[v]] == 1)
	{
		us[v] = 3;
		x = a[v];
		return;
	}
	if (!us[a[v]]) dfs(a[v]);
	if (x)
	{
		us[v] = 3;
		if (x == v) x = 0;
		return;
	}
	us[v] = 2;
}

void dffs(int v, int f = 0)
{
	if (!f) an1++;
	else an2++;
	for (int i : pr[v])
		if (us[i] != 3)
			dffs(i, f ^ 1);
}

int main()
{
#ifdef _DEBUG
	freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
#else
	//freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
	//freopen(TASK".in", "r", stdin), freopen(TASK".out", "w", stdout);
#endif
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin >> n;
	for (int i = 1; i <= n; ++i)
	{
		cin >> a[i];
		pr[a[i]].inb(i);
	}
	for (int i = 1; i <= n; ++i)
		if (!us[i])
			dfs(i);
	for (int i = 1; i <= n; ++i)
		if (us[i] == 3)
		{
			an2 = 0, an1 = 0;
			dffs(i);
			vv[i] = { an1, an2 };
		}
	vi tt;
	for(int i = 1; i <= n; ++i)
		if (us[i] == 3)
		{
			tt.inb(i);
			int j = a[i];
			while (j != i)
			{
				tt.inb(j);
				j = a[j];
			}
			break;
		}
	int ans = 0;
	for (int qq = 0; qq < 5; ++qq)
	{
		dp[qq][1] = vv[tt[qq]].X;
		dp[qq][0] = -INF;
		for (int i = qq + 1; i < tt.size(); ++i)
		{
			dp[i][0] = max(dp[i - 1][0] + vv[tt[i]].Y, dp[i - 1][1] + vv[tt[i]].Y);
			dp[i][1] = dp[i - 1][0] + vv[tt[i]].X;
		}
		ans = max(ans, dp[tt.size() - 1][0]);
		tt.inb(tt[qq]);
	}
	cout << ans;
}