import sys
input = lambda : sys.stdin.readline().rstrip()

sys.setrecursionlimit(2*10**5+10)
write = lambda x: sys.stdout.write(x+"\n")
debug = lambda x: sys.stderr.write(x+"\n")
writef = lambda x: print("{:.12f}".format(x))

class BIT:
    ### BIT binary
    def __init__(self, n, values=None):
        self.bit = [0]*(n+1)
        self.n = n
        self.total = 0
        if values is not None:
            for i,v in enumerate(values):
                self.add(i,v)
                self.total += v
    def check(self):
        l = []
        prv = 0
        for i in range(1,self.n+1):
            val = self.query(i)
            l.append(val-prv)
            prv = val
        print(" ".join(map(str, l)))
    #a1 ~ aiまでの和 O(logn)
    def query(self,i):
        res = 0
        while i > 0:
            res += self.bit[i]
            # res %= M
            i -= i&(-i)
        return res
    def get(self,i):
        return self.query(i+1) - self.query(i)
    #ai += x(logN)
    def add(self,i,x):
        i += 1
        if i==0:
            raise RuntimeError
        self.total += x
        while i <= self.n:
            self.bit[i] += x
            # self.bit[i] %= M
            i += i&(-i)
    def index(self, v):
        """a0,...,aiの和がv以上になる最小のindexを求める
        存在しないとき配列サイズを返す
        """
        if v <= 0:
            return 0
        if self.total<v:
            return self.n
        x = 0
        r = 1
        while r < self.n:
            r = r << 1;
        ll = r
        while ll>0:
            if x+ll<self.n and self.bit[x+ll]<v:
                v -= self.bit[x+ll]
                x += ll
            ll = ll>>1
        return x

    
n = int(input())
a = list(map(int, input().split()))
ns = [[] for _ in range(n)]
for u,p in enumerate(a):
    ns[u+1].append(p)
    ns[p].append(u+1)
    
bit = BIT(n)

# 深さ優先探索 (巻き戻しあり) dfs tree
q = [(0, -1)]
ans = 0
while q:
    u,prv = q.pop()
    if u<0:
        # 返るときの処理
        u = ~u
        bit.add(u, -1)
    else:
        q.append((~u,prv))
        ans += bit.query(u)
        bit.add(u, 1)
        for v in ns[u]:
            # 進むときの処理
            if v==prv:
                continue
            q.append((v,u))
print(ans)