from collections import defaultdict
import sys
sys.setrecursionlimit(10 ** 6)


class FenwickTree:
    def __init__(self, n):
        self.data = [0] * (n + 10)

    def add(self, p, x):
        assert 0 <= p
        p += 1
        while p < len(self.data):
            self.data[p] += x
            p += p & -p

    def sum(self, p):
        """区間 [0, p] の和"""
        assert 0 <= p
        p += 1
        s = 0
        while p > 0:
            s += self.data[p]
            p -= p & -p
        return s

    def rangesum(self, l, r):
        """区間 [l, r] の和"""
        assert 0 <= l <= r
        s = self.sum(r)
        if l > 0:
            s -= self.sum(l-1)
        return s


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

adj = defaultdict(list)
for i in range(N-1):
    par = A[i]
    adj[par].append(i+1)


def dfs(v):
    res = ft.sum(v)
    ft.add(v, 1)
    for to in adj[v]:
        res += dfs(to)
    ft.add(v, -1)
    return res


ft = FenwickTree(N)
ans = dfs(0)
print(ans)