class BIT:
    def __init__(self, n):
        self.n = n
        self.bit = [0]*(self.n+1) # 1-indexed

    def init(self, init_val):
        for i, v in enumerate(init_val):
            self.add(i, v)

    def add(self, i, x):
        # i: 0-indexed
        i += 1 # to 1-indexed
        while i <= self.n:
            self.bit[i] += x
            i += (i & -i)

    def sum(self, i, j):
        # return sum of [i, j)
        # i, j: 0-indexed
        return self._sum(j) - self._sum(i)

    def _sum(self, i):
        # return sum of [0, i)
        # i: 0-indexed
        res = 0
        while i > 0:
            res += self.bit[i]
            i -= i & (-i)
        return res

class RangeAddBIT:
    def __init__(self, n):
        self.n = n
        self.bit1 = BIT(n)
        self.bit2 = BIT(n)

    def init(self, init_val):
        self.bit2.init(init_val)

    def add(self, l, r, x):
        # add x to [l, r)
        # l, r: 0-indexed
        self.bit1.add(l, x)
        self.bit1.add(r, -x)
        self.bit2.add(l, -x*l)
        self.bit2.add(r, x*r)

    def sum(self, l, r):
        # return sum of [l, r)
        # l, r: 0-indexed
        return self._sum(r) - self._sum(l)

    def _sum(self, i):
        # return sum of [0, i)
        # i: 0-indexed
        return self.bit1._sum(i)*i + self.bit2._sum(i)

import sys
input = sys.stdin.buffer.readline

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

par = [-1]*n
ch = [[] for _ in range(n)]
for i, a in enumerate(A):
    par[i+1] = a
    ch[a].append(i+1)

root = 0

s = [root]
eulerTour = []
left = [0]*n
right = [-1]*n
depth = [-1]*n

num = -1
de = -1

while s:
    q = s.pop()
    if q >= 0:
        num += 1
        eulerTour.append(q)
        left[q] = num
        right[q] = num
        s.append(~q)
        de += 1
        depth[q] = de
        for v in ch[q]:
            s.append(v)
    else:
        de -= 1
        if ~q != root:
            eulerTour.append(par[~q])
            num += 1
            right[par[~q]]  = num

#print(eulerTour)
#print(left)
#print(right)

bit = RangeAddBIT(2*n+1)
ans = 0
for i in range(n):
    ans += bit.sum(left[i], left[i]+1)
    bit.add(left[i], right[i]+1, 1)
print(ans)