class Bit:
    def __init__(self, n):
        self.size = n
        self.n0 = 1 << (n.bit_length() - 1)
        self.tree = [0] * (n + 1)
    
    def range_sum(self, l, r):
        return self.sum(r - 1) - self.sum(l - 1)
        
    def sum(self, i):
        i += 1
        s = 0
        while i > 0:
            s += self.tree[i]
            i -= i & -i
        return s
        
    def get(self, i):
        return self.sum(i) - self.sum(i - 1)
 
    def add(self, i, x):
        i += 1
        while i <= self.size:
            self.tree[i] += x
            i += i & -i
         
    def lower_bound(self, x):
        pos = 0
        plus = self.n0
        while plus > 0:
            if pos + plus <= self.size and self.tree[pos + plus] < x:
                x -= self.tree[pos + plus]
                pos += plus
            plus //= 2
        return pos

def EulerTour(n, edges, root=0):
    L = [-1] * n
    R = [0] * n
    stack = [(root, 1), (root, 0)]
    ind = 0
    while stack:
        pos, t = stack.pop()
        if t == 0:
            L[pos] = ind
            ind += 1
            for npos in edges[pos]:
                if L[npos] != -1:
                    continue
                stack.append((npos, 1))
                stack.append((npos, 0))
        else:
            R[pos] = ind
    
    return L, R

n = int(input())
A = list(map(int, input().split()))
edges = [[] for _ in range(n)]
for i, p in enumerate(A, 1):
    edges[p].append(i)

L, R = EulerTour(n, edges)

bit = Bit(n)
ans = 0
for i in range(n - 1, -1, -1):
    ans += bit.range_sum(L[i], R[i])
    bit.add(L[i], 1)
print(ans)