import typing
import sys
sys.setrecursionlimit(200050)

class FenwickTree:
    '''Reference: https://en.wikipedia.org/wiki/Fenwick_tree'''

    def __init__(self, n: int = 0) -> None:
        self._n = n
        self.data = [0] * n

    def add(self, p: int, x: typing.Any) -> None:
        assert 0 <= p < self._n

        p += 1
        while p <= self._n:
            self.data[p - 1] += x
            p += p & -p

    def sum(self, left: int, right: int) -> typing.Any:
        assert 0 <= left <= right <= self._n

        return self._sum(right) - self._sum(left)

    def _sum(self, r: int) -> typing.Any:
        s = 0
        while r > 0:
            s += self.data[r - 1]
            r -= r & -r

        return s

N = int(input())
A = list(map(int, input().split()))
ft = FenwickTree(N)
E = [[] for _ in range(N)]
for i, a in enumerate(A, start=1):
    E[a].append(i)

ans = 0
def dfs(x):
    global ans
    for y in E[x]:
        ans += ft.sum(0, y)
        ft.add(y, 1)
        dfs(y)
        ft.add(y, -1)

ft.add(0, 1)
dfs(0)
print(ans)