#region Header
#!/usr/bin/env python3
# from typing import *

import sys
import io
import math
import collections
import decimal
import itertools
import bisect
import heapq

def input():
    return sys.stdin.readline()[:-1]

sys.setrecursionlimit(1000000)
#endregion

# _INPUT = """3
# 2 0
# """
# sys.stdin = io.StringIO(_INPUT)

# 最もシンプル
class BIT:
    """
    Binary Indexed Tree (Fenwick Tree), 1-indexed
    """

    def __init__(self, n):
        """
        Parameters
        ----------
        n : int
            要素数。index は 0..n になる。
        """
        self.size = n
        self.data = [0] * (n+1)
        # self.depth = n.bit_length()

    def add(self, i, x):
        while i <= self.size:
            self.data[i] += x
            i += i & -i

    def get_sum(self, i):
        s = 0
        while i > 0:
            s += self.data[i]
            i -= i & -i
        return s

    def get_rsum(self, l, r):
        """
        [l, r) の sum
        """
        return self.get_sum(r) - self.get_sum(l-1)

def dfs(G, bit, N, pos):

    n = bit.get_sum(pos+1)
    bit.add(pos+1, 1)

    for next_pos in G[pos]:
        n += dfs(G, bit, N, next_pos)

    bit.add(pos+1, -1)

    return n


def main():
    N = int(input())
    A = list(map(int, input().split()))

    G = [list() for _ in range(N)]
    for i in range(N-1):
        G[A[i]].append(i+1)

    bit = BIT(N)
    ans = dfs(G, bit, N, 0)
    print(ans)

if __name__ == '__main__':
    main()