#include <bits/stdc++.h>
using namespace std;

struct iofast_t {
    iofast_t() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} iofast;

struct uns_t {} uns;
template <typename Element, typename Head, typename ...Args>
auto vec(Element init, Head arg, Args ...args) {
    if constexpr (sizeof...(Args) == 0) return std::vector(arg, init);
    else return std::vector(arg, vec(init, args...));
}
template <typename Element, typename Head, typename ...Args>
auto vec(uns_t, Head arg, Args ...args) {
    return vec(Element(), arg, args...);
}

template <typename T, typename Compare = less<T>>
T &chmin(T &l, T r, Compare &&f = less<T>()) { return l = min(l, r, f); }
template <typename T, typename Compare = less<T>>
T &chmax(T &l, T r, Compare &&f = less<T>()) { return l = max(l, r, f); }

#include <atcoder/segtree>

template <auto op, auto e>
struct segtree;

template <typename S, S (*op)(S, S), S (*e)()>
struct segtree<op, e> : atcoder::segtree<S, op, e> {
    using atcoder::segtree<S, op, e>::segtree;
};

int op(int x, int y) {
    return x + y;
}

int e() {
    return 0;
}

int main() {
    int n; cin >> n;
    auto g = vec<int>(uns, n, 0);
    for (int i = 1; i < n; ++i) {
        int a; cin >> a;
        g[a].push_back(i);
        g[i].push_back(a);
    }

    int64_t ans = 0;

    segtree<op, e> seg(n);
    auto dfs = [&](auto &&self, int v, int p = -1) -> void {
        ans += seg.prod(0, v);

        seg.set(v, 1);
        for (auto u : g[v]) {
            if (u == p) {
                continue;
            }
            self(self, u, v);
        }
        seg.set(v, 0);
    };

    dfs(dfs, 0);

    cout << ans << endl;
}