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

template <class T> struct fenwick_tree {
    using U = T;

    public:
    fenwick_tree() : _n(0) {}
    fenwick_tree(int n) : _n(n), data(n) {}

    void add(int p, T x) {
        assert(0 <= p && p < _n);
        p++;
        while (p <= _n) {
            data[p - 1] += U(x);
            p += p & -p;
        }
    }

    T sum(int l, int r) {
        assert(0 <= l && l <= r && r <= _n);
        return sum(r) - sum(l);
    }

    private:
    int _n;
    std::vector<U> data;

    U sum(int r) {
        U s = 0;
        while (r > 0) {
            s += data[r - 1];
            r -= r & -r;
        }
        return s;
    }
};

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int N;
    cin >> N;
    vector<vector<int>> G(N);
    fenwick_tree<int> fw(N);
    for(int i = 1; i < N; i++){
        int p;
        cin >> p;
        G[p].emplace_back(i);
    }
    ll ans = 0;
    auto dfs = [&](auto self, int v) -> void {
        ans += fw.sum(0, v);
        fw.add(v, 1);
        for(auto &&u : G[v]) self(self, u);
        fw.add(v, -1);
    };
    dfs(dfs, 0);
    cout << ans << '\n';
}