class Fenwick_Tree:
    def __init__(self, n):
        self._n = n
        self.data = [0] * n

    def add(self, p, x):
        assert 0 <= p < self._n
        p += 1
        while p <= self._n:
            self.data[p - 1] += x
            p += p & -p

    def sum(self, l, r):
        assert 0 <= l <= r <= self._n
        return self._sum(r) - self._sum(l)

    def _sum(self, r):
        s = 0
        while r > 0:
            s += self.data[r - 1]
            r -= r & -r
        return s
    
    def get(self, k):
        k += 1
        x, r = 0, 1
        while r < self._n:
            r <<= 1
        len = r
        while len:
            if x + len - 1 < self._n:
                if self.data[x + len - 1] < k:
                    k -= self.data[x + len - 1]
                    x += len
            len >>= 1
        return x
    

def non_rec_dfs(s):
    stack = []
    stack.append(~s)
    stack.append(s)
    par = [-1] * N
    global ans
    while stack:
        u = stack.pop()
        if u >= 0:
            ans += T.sum(0, u)
            T.add(u, 1)
            stack.append(~u)
            for v in G[u]:
                if v == par[u]:
                    continue
                par[v] = u
                stack.append(v)
        else:
            u = ~u
            T.add(u, -1)    

N = int(input())
A = list(map(int, input().split()))
G = [[] for i in range(N)]
for i, a in enumerate(A):
    i += 1
    G[i].append(a)
    G[a].append(i)
    
ans = 0
T = Fenwick_Tree(N)
non_rec_dfs(0)
print(ans)