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

template<typename T>
struct Ftree {
  vector<T> dat;
  Ftree(int n) : dat(n + 1) {}
  void add(int x, T v) { for (int i = x + 1; i < dat.size(); i += i & -i) dat[i] += v; }
  T sum(int x) {
    T r = 0;
    for (int i = x + 1; i; i -= i & -i) r += dat[i];
    return r;
  }
};

int main() {
  ios::sync_with_stdio(false);

  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);
    }
  }

  int64_t res = 0; {
    Ftree<int> ftree(N);
    function<void(int, int)> dfs = [&](int u, int fa) {
      res += ftree.sum(u);
      ftree.add(u, +1);
      for (int v : G[u]) if (v != fa) dfs(v, u);
      ftree.add(u, -1);
    };
    dfs(0, -1);
  }

  cout << res << endl;
}