#include <bits/stdc++.h>
using namespace std;

const int N = 2e5 + 10;

int n, a[N];
int vis[N];
int dep[N];

int ans = N;

void dfs (int x, int d, int v) {
//  cout << x << ' ' << d << ' ' << dep[x] << endl;
    if (vis[x]) {
        if (v == vis[x]) ans = min(ans, d - dep[x]);
        return;
    }
    vis[x] = v;
    dep[x] = d;
    dfs(a[x], d + 1, v);
}

int main () {
    cin >> n;
    for (int i = 1; i <= n; i ++) {
        cin >> a[i];
    }
    for (int i = 1; i <= n; i ++) {
        if (vis[i]) continue;
        dfs(i, 1, i);
    }
    cout << ans << endl;
    return 0;
}