#include <iostream>

#include <cstring>

#include <cmath>

#define maxn 200005

using namespace std;

int n, nxt[maxn];

int dfn[maxn], color[maxn], ans = 0x7f7f7f7f;

void dfs(int v, int d, int c)

{

    if (dfn[v])

    {

        if(color[v] == c)

            ans = min(ans, d - dfn[v]);

    }

    else

    {

        dfn[v] = d;

        color[v] = c;

        dfs(nxt[v], d + , c);

    }

}

int main()

{

    ios::sync_with_stdio(false);

    cin >> n;

    for (int i = ; i <= n; i++)

        cin >> nxt[i];

    for (int i = ; i <= n; i++)

    {

        if (!dfn[i])

            dfs(i, , i);

    }

    cout << ans;

    return ;

}