// 基本
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
// 型名の省略
using ll = long long;
template <class T>
using vc = vector<T>;
template <class T>
using vvc = vector<vc<T>>;
template <class T>
using vvvc = vector<vvc<T>>;
template <class T>
using vvvvc = vector<vvvc<T>>;
template <class T>
using vvvvvc = vector<vvvvc<T>>;
template <class T>
using pq = priority_queue<T>;
template <class T>
using pqg = priority_queue<T, vector<T>, greater<T>>;
// 定数
constexpr long long MOD = 1000000007LL;
template <class T>
constexpr T INF = 0;
template <>
constexpr int INF<int> = 1001001001;
template <>
constexpr long long INF<long long> = 1LL << 61;
template <>
constexpr double INF<double> = INF<long long>;
template <>
constexpr long double INF<long double> = INF<long long>;
// 便利関数
// 入出力処理
template <class... T>
void input(T &...a)
{
    (cin >> ... >> a);
}
void print()
{
    cout << '\n';
}
template <class T, class... Ts>
void print(const T &a, const Ts &...b)
{
    cout << a;
    (cout << ... << (cout << ' ', b));
    cout << '\n';
}
// 繰り返し処理
#define overload4(a, b, c, d, e, ...) e
#define rep1(a) for (int i = 0; i < a; i++)
#define rep2(i, a) for (int i = 0; i < a; i++)
#define rep3(i, a, b) for (int i = a; i < b; i++)
#define rep4(i, a, b, c) for (int i = a; i < b; i += c)
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
// 配列処理
template <class T>
bool operator==(const vector<T> &a, const vector<T> &b)
{
    return (a.size() == b.size()) && equal(a.cbegin(), a.cend(), b.cbegin());
}
template <class T>
bool operator!=(const vector<T> &a, const vector<T> &b)
{
    return !(a == b);
}
// 最小・最大処理
template <class T>
inline bool chmax(T &a, T b)
{
    if (a < b)
    {
        a = b;
        return true;
    }
    return false;
}
template <class T>
inline bool chmin(T &a, T b)
{
    if (a > b)
    {
        a = b;
        return true;
    }
    return false;
}
template <class... Args>
inline auto all_max(Args... args)
{
    return max(initializer_list<common_type_t<Args...>>{args...});
}
template <class... Args>
inline auto all_min(Args... args)
{
    return min(initializer_list<common_type_t<Args...>>{args...});
}
// 追加ライブラリ
using S = int;
S op(S l, S r)
{
    return l + r;
}
S e()
{
    return 0;
}
/// ここからコードを書く

int main()
{
    cin.tie(0);
    int n;
    input(n);
    vvc<int> a(n);
    rep(i, n - 1)
    {
        int at;
        input(at);
        a[at].push_back(i + 1);
    }
    segtree<S, op, e> seg(n);
    ll ans = 0;
    auto dfs = [&](auto self, int cu) -> void
    {
        ans += seg.prod(0, cu);
        seg.set(cu, 1);
        for (int ne : a[cu])
        {
            self(self, ne);
        }
        seg.set(cu, 0);
    };
    dfs(dfs, 0);
    print(ans);
    return 0;
}