#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = false;
//---------------------------------//

template<typename T>
struct BinaryIndexedTree {
	using value_type = T;
	using const_reference = const value_type &;
	using F = std::function<value_type(const_reference, const_reference)>;
	using size_type = std::size_t;
	
	BinaryIndexedTree(size_type n, const F & f, const_reference id_elem) : n(n), f(f), id_elem(id_elem) {
		node.resize(n + 1, id_elem);
	}
	
	size_type size() const noexcept {
		return n;
	}
	
	void add(size_type i, const_reference x) {
		assert(i < size());
		++i;
		for (; i <= size(); i += i & -i) node[i] = f(node[i], x);
	}
	
	// [0, i)
	value_type sum(size_type i) const {
		assert(i <= size());
		value_type res = id_elem;
		for (; i > 0; i -= i & -i) res = f(res, node[i]);
		return res;
	}
	
	// sum[0, r] <= x を満たす最小の r を返す (存在しなければ size())
	size_type lower_bound(const_reference x) const {
		size_type res = 0;
		size_type s = id_elem, w = 1;
		while (w < size()) w <<= 1;
		for (; w > 0; w >>= 1) {
			if (res + w <= size()) {
				value_type cur = f(s, node[res + w]);
				if (cur < x) {
					res += w;
					s = cur;
				}
			}
		}
		return res;
	}
	
private:
	size_type n;
	F f;
	value_type id_elem;
	std::vector<value_type> node;
};

int main() {
	int N;
	cin >> N;
	vector<vector<int>> g(N);
	REP(i, N - 1) {
		int a;
		scanf("%d", &a);
		g[a].emplace_back(i + 1);
	}
	BinaryIndexedTree<int> bit(N, [](int x, int y) { return x + y; }, 0);
	
	ll ans = 0;
	auto dfs = [&](auto self, int u) -> void {
		ans += bit.sum(u);
		bit.add(u, 1);
		for (int v : g[u]) self(self, v);
		bit.add(u, -1);
	};
	dfs(dfs, 0);
	cout << ans << endl;
}