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

// one-based numbering
template<class T> struct Fenwick {
    vector<T> bit; int N;
    Fenwick(int n) {
      N = n;
      bit.resize(n+1, 0);
    }
    void add(int a, T w) {
      for (int x = a; x <= N; x += x & -x) bit[x] += w;
    }
    T sum(int a) {
      T ret = 0;
      for (int x = a; x > 0; x -= x & -x) ret += bit[x];
      return ret;
    }
};

long long dfs(int now, Fenwick<long long> &f, vector<int> v[]) {
    long long ret = 0;
    ret += f.sum(now+1); f.add(now+1, 1);
    for (int i = 0; i < (int) v[now].size(); i++) {
        ret += dfs(v[now][i], f, v);
    }
    f.add(now+1, -1);
    return ret;
}

int main() {
    int n; cin >> n;
    vector<int> v[n];
    for (int i = 1; i < n; i++) {
        int k; cin >> k;
        v[k].push_back(i);
    }
    Fenwick<long long> fenwick(n+1);
    cout << dfs(0, fenwick, v) << endl;
    return 0;
}