import sys; input = sys.stdin.buffer.readline
sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

class SegmentTree(object):
	#N:処理する区間の長さ
	def __init__(self, N):
		self.N0 = 2 ** (N - 1).bit_length()
		self.data = [0] * (2 * self.N0)

	#k番目の値をxに更新
	def update(self, k, x):
		k += self.N0 - 1
		self.data[k] = x
		while k > 0:
			k = (k - 1) // 2
			self.data[k] = self.data[2 * k + 1] + self.data[2 * k + 2]

	#区間[l, r]の和
	def query(self, l, r):
		L = l + self.N0; R = r + self.N0 + 1
		m = 0
		while L < R:
			if R & 1:
				R -= 1
				m += self.data[R - 1]
			if L & 1:
				m += self.data[L - 1]
				L += 1
			L >>= 1; R >>= 1

		return m

class Graph(object):
	def __init__(self):
		self.graph = defaultdict(list)

	def __len__(self):
		return len(self.graph)

	def add_edge(self, a, b):
		self.graph[a].append(b)

ans = 0
def DFS(G, Seg, node):
	Seg.update(node, 1)
	for i in G.graph[node]:
		# if visit[i] != 1:
		# 	visit[i] = 1
		DFS(G, Seg, i)
	global ans
	ans += Seg.query(0, node) - 1
	Seg.update(node, 0)


#処理内容
def main():
	N = int(input())
	A = getlist()
	Seg = SegmentTree(N + 1)
	G = Graph()
	for i in range(N - 1):
		G.add_edge(A[i], i + 1)

	# ans = 0
	DFS(G, Seg, 0)
	print(ans)


if __name__ == '__main__':
	main()