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

//repetition
#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define rep(i, n) for(ll i = 0; i < (ll)(n); i++)

//container util
#define all(x) (x).begin(),(x).end()

//typedef
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VLL;
typedef vector<VLL> VVLL;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef pair<ll, ll> PLL;

//const value
//const ll MOD = 1e9 + 7;
//const int dx[] = {0,1,0,-1};//{0,0,1,1,1,-1,-1,-1};
//const int dy[] = {1,0,-1,0};//{1,-1,0,1,-1,0,1,-1};

//conversion
inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
inline ll toLL(string s) {ll v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}

struct BIT{
  int n;
  VI nodes;
  void init(int N){
    nodes.resize(N+1,0);
    n = N;
  }
  void add(int i, int x){
    for(int idx = i; idx <= n; idx += idx & (-idx)){
      nodes[idx] += x;
    }
  }

  ll sum(int x){
    ll res = 0;
    for(int idx = x; idx > 0 ; idx -= idx & (-idx)){
      res += nodes[idx];
    }
    return res;
  }

};

ll dfs(int current_node, VVI& edge, BIT & bit){
  ll res = 0;
  // 二分探索をしてcurrent_nodeよりも小さい要素を探索

  res += bit.sum(current_node+1);
  bit.add(current_node+1,1);
  for(int node :edge[current_node]){
    res += dfs(node,edge,bit);
  }
  bit.add(current_node+1,-1);

  return res;
}
int main(){
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  VI a(n);
  VVI edge(n);
  FOR(i,1,n){
    cin >> a[i];
    edge[a[i]].push_back(i);
  }

  BIT bit;
  bit.init(n);
  ll ans = dfs(0,edge,bit);
  cout << ans << endl;
  return 0;
}