import sys

sys.setrecursionlimit(10**6)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def MI(): return map(int, sys.stdin.buffer.readline().split())
def MI1(): return map(int1, sys.stdin.buffer.readline().split())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def BI(): return sys.stdin.buffer.readline().rstrip()
def SI(): return sys.stdin.buffer.readline().rstrip().decode()
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [[(-1, 0), (1, 0)], [(0, -1), (0, 1)]]
inf = 10**16
md = 998244353
# md = 10**9+7

class BitSum:
    def __init__(self, n):
        self.n = n+1
        self.table = [0]*self.n

    def add(self, i, x):
        i += 1
        while i < self.n:
            self.table[i] += x
            i += i & -i

    # [0,i]の和
    def sum(self, i):
        i += 1
        res = 0
        while i > 0:
            res += self.table[i]
            i -= i & -i
        return res

n=II()
to=[[] for _ in range(n)]
for c,p in enumerate(MI(),1):
    to[p].append(c)

bit=BitSum(n)

def dfs(u):
    stack=[u]
    vis=[False]*n
    res=0
    while stack:
        u=stack.pop()
        if vis[u]:
            bit.add(u, -1)
        else:
            vis[u]=True
            stack.append(u)
            res+=bit.sum(u)
            bit.add(u,1)
            for v in to[u]:
                stack.append(v)
    return res

print(dfs(0))