#ifndef LOCAL
#include <bits/stdc++.h>

using namespace std;

#define debug(...) (void(0))
#else
#include "algo/debug.h"
#endif

#include <atcoder/segtree>
using S = int64_t;
S op(S a, S b) { return a + b; }
S e() { return 0; }
namespace std {

template <class Fun>
class y_combinator_result {
    Fun fun_;

   public:
    template <class T>
    explicit y_combinator_result(T &&fun) : fun_(std::forward<T>(fun)) {}

    template <class... Args>
    decltype(auto) operator()(Args &&...args) {
        return fun_(std::ref(*this), std::forward<Args>(args)...);
    }
};

template <class Fun>
decltype(auto) y_combinator(Fun &&fun) {
    return y_combinator_result<std::decay_t<Fun>>(std::forward<Fun>(fun));
}

}  // namespace std

void solve() {
    int N; cin >> N;
    vector<vector<int>> G(N);
    for(int i = 1; i < N; i++) {
        int a; cin >> a;
        G[a].push_back(i);
        G[i].push_back(a);
    }
    atcoder::segtree<S, op, e> seg(N);
    S ans = 0;
    y_combinator([&](auto self, int v, int p = -1) -> void {
        seg.set(v, 1);
        for(const auto&to: G[v]) if(to != p) {
            self(to, v);
        }
        ans += seg.prod(0, v);
        seg.set(v, 0);
    })(0);
    cout << ans << endl;
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int tt = 1;
    // std::cin >> tt;
    while(tt--) {
        solve();
    }
}