import sys

sys.setrecursionlimit(10 ** 9)


class Bit:
    """1-indexed"""

    def __init__(self, n):
        self.size = n
        self.tree = [0] * (n + 1)

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

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


N = int(input())
A = map(int, input().split())
T = [[] for _ in range(N)]
for i, a in enumerate(A, 1):
    T[a].append(i)

bit = Bit(N)


def dfs(v):
    res = bit.sum(v)
    bit.add(v + 1, 1)
    for x in T[v]:
        res += dfs(x)
    bit.add(v + 1, -1)
    return res


print(dfs(0))