using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var a = NList;
        var tree = new List<int>[n];
        for (var i = 0; i < tree.Length; ++i) tree[i] = new List<int>();
        for (var i = 0; i < a.Length; ++i)
        {
            tree[a[i]].Add(i + 1);
        }
        var ft = new AtCoder.FenwickTree<int>(n);
        var ans = 0L;
        DFS(0, tree, ft, ref ans);
        WriteLine(ans);
    }
    static void DFS(int cur, List<int>[] tree, AtCoder.FenwickTree<int> ft, ref long ans)
    {
        ans += ft.Sum(cur);
        ft.Add(cur, 1);
        foreach (var next in tree[cur])
        {
            DFS(next, tree, ft, ref ans);
        }
        ft.Add(cur, -1);
    }
}