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

#define int long long
#define rep(i,l,r) for(int i=(int)(l);i<(int)(r);i++)
#define all(x) (x).begin(),(x).end()
#define pb push_back
template<class T>bool chmax(T &a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T &a,T b){if(a>b){a=b;return 1;}return 0;}

typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;

const int inf = 1LL<<60;
const int mod = 1e9 + 7;
const double eps = 1e-9;

/*{
}*/

template<class T>
class BinaryIndexedTree
{
public:
  int n;
  vector<T> bit;

  BinaryIndexedTree():n(-1){}
  BinaryIndexedTree(int n_):n(n_),bit(n_+1,0){}
  BinaryIndexedTree(int n_, T d):n(n_),bit(n_+1,d){}

  T sum(int i)
  {
    T s = 0;
    while(i > 0){
      s += bit[i];
      i -= i&-i;
    }
    return s;
  }

  void add(int i, T x)
  {
    if(i == 0) return;
    while(i <= n){
      bit[i] += x;
      i += i&-i;
    }
  }

  T sum0(int i)
  {
    return sum(i+1);
  }

  void add0(int i, T x)
  {
    add(i+1, x);
  }

  T query(int l, int r)
  {
    return sum(r-1)-sum(l-1);
  }

  T query0(int l, int r)
  {
    return sum(r)-sum(l);
  }
};

int n;
vi g[200000];
BinaryIndexedTree<int> bit;
int ans;

void dfs(int v)
{
  ans += bit.query0(0, v);
  bit.add0(v, 1);
  for(int to : g[v]){
    dfs(to);
  }
  bit.add0(v, -1);
}

signed main()
{
  cin >> n;
  rep(i, 1, n){
    int a;
    cin >> a;
    g[a].pb(i);
  }

  bit = BinaryIndexedTree<int>(n);
  dfs(0);

  cout << ans << endl;

  return 0;
}