#include <iostream>
#include <string>
#include <cstdlib>
#include <cmath>
#include <vector>
#include <map>
#include <set>
#include <algorithm>
#include <queue>
#include <stack>
#include <functional>
#include <bitset>
#include <assert.h>
using namespace std;
typedef long long ll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<char> vc;
typedef vector<string> vs;
typedef vector<bool> vb;
typedef vector<double> vd;
typedef pair<ll,ll> P;
typedef vector<P> vpl;
typedef tuple<ll,ll,ll> tapu;
#define rep(i,n) for(ll i=0; i<(n); i++)
#define REP(i,a,b) for(int i=(a); i<(b); i++)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
const int inf = 1<<30;
const ll linf = 1LL<<62;
const int MAX = 510000;
ll dy[8] = {0,1,0,-1,1,-1,1,-1};
ll dx[8] = {1,0,-1,0,1,-1,-1,1};
const double pi = acos(-1);
const double eps = 1e-7;
template<typename T1,typename T2> inline bool chmin(T1 &a,T2 b){
	if(a>b){
		a = b; return true;
	}
	else return false;
}
template<typename T1,typename T2> inline bool chmax(T1 &a,T2 b){
	if(a<b){
		a = b; return true;
	}
	else return false;
}
template<typename T1,typename T2> inline void print2(T1 a, T2 b){cout << a << " " << b << "\n";}
template<typename T1,typename T2,typename T3> inline void print3(T1 a, T2 b, T3 c){
	cout << a << " " << b << " " << c << "\n";
}
const int mod = 1e9 + 7;
//const int mod = 998244353;

template< typename T >
struct BinaryIndexedTree {
  vector< T > data;

  BinaryIndexedTree(int sz) {
    data.assign(++sz, 0);
  }

  T sum(int k) {
    T ret = 0;
    for(++k; k > 0; k -= k & -k) ret += data[k];
    return (ret);
  }

  void add(int k, T x) {
    for(++k; k < data.size(); k += k & -k) data[k] += x;
  }
};

ll ans;
BinaryIndexedTree<ll> bit(202020);
vvl G(202020);

void dfs(ll u, ll p){
	bit.add(u+1,1);
	ans += bit.sum(u);
	for(auto v : G[u]){
		if(v != p) dfs(v,u);
	}
	bit.add(u+1,-1);
}


int main(){
	ll n; cin >> n;
	rep(i,n-1){
		ll a; cin >> a;
		G[i+1].push_back(a);
		G[a].push_back(i+1);
	}
	dfs(0,-1);
	cout << ans << endl;
}