#include <iostream>
#include <algorithm>
#include <queue>
#include <vector>
using namespace std;
vector<int> graph[50001];

int main() {
    int n;
    cin >> n;
    
    for(int i = 0; i < n; i++) {
        int x;
        cin >> x;
        x--;
        graph[i].push_back(x);
    }
    
    vector<bool> visited_bfs(n, false);
    int res = 0;
    for(int i = 0; i < n; i++) {
        if(!visited_bfs[i]) {
            queue<int> q;
            q.push(i);
            
            vector<bool> visited(n, false);
            visited[i] = true;
            int nodes = 1;
            while(!q.empty()) {
                int node = q.front();
                q.pop();
                
                for(int j = 0; j < (int) graph[node].size(); j++) {
                    int neighbour = graph[node][j];
                    
                    if(!visited[neighbour]) {
                        visited[neighbour] = true;
                        visited_bfs[neighbour] = true;
                        q.push(neighbour);
                        nodes++;
                        res = max(res, nodes);
                    }
                    
                }
            }
        }
    }
    cout << res << endl;
    
    return 0;
}