mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    class Bit:
        def __init__(self, n):
            self.size = n
            self.tree = [0] * (n + 1)

        def sum(self, i):
            s = 0
            while i > 0:
                s += self.tree[i]
                i -= i & -i
            return s

        def add(self, i, x):
            while i <= self.size:
                self.tree[i] += x
                i += i & -i

        def lower_bound(self, w):
            if w <= 0:
                return 0
            x = 0
            k = 1 << (self.size.bit_length() - 1)
            while k:
                if x + k <= self.size and self.tree[x + k] < w:
                    w -= self.tree[x + k]
                    x += k
                k >>= 1
            return x + 1

    # adj[0] must be empty list
    def EulerTour(adj, root):
        st = [root]
        ret = []
        seen = [0] * len(adj)
        par = [0] * len(adj)
        depth = [0] * len(adj)
        while st:
            v = st.pop()
            if seen[v]:
                ret.append(v)
                continue
            ret.append(v)
            seen[v] = 1
            if par[v] != 0:
                st.append(par[v])
            for u in adj[v]:
                if seen[u] == 0:
                    st.append(u)
                    par[u] = v
                    depth[u] = depth[v] + 1

        return ret, depth

    N = int(input())
    A = list(map(int, input().split()))

    adj = [[] for _ in range(N+1)]
    for i in range(N-1):
        v = i+2
        p = A[i] + 1
        adj[v].append(p)
        adj[p].append(v)

    et, depth = EulerTour(adj,1)
    bit = Bit(len(et))
    cnt = [0] * (N+1)
    v_idx = [[] for _ in range(N+1)]
    for i, v in enumerate(et):
        cnt[v] += 1
        v_idx[v].append(i+1)
    for i, v in enumerate(et):
        bit.add(i+1, 1 / cnt[v])
    ans = 0
    for v in range(1, N+1):
        ans += bit.sum(v_idx[v][-1]) - bit.sum(v_idx[v][0]-1) - 1
        for i in v_idx[v]:
            bit.add(i, -1 / cnt[v])
    print(round(ans))


if __name__ == '__main__':
    main()