#include <bits/stdc++.h>
//#include<boost/multiprecision/cpp_int.hpp>
//#include<boost/multiprecision/cpp_dec_float.hpp>
//#include <atcoder/all>
#define rep(i, a) for (int i = (int)0; i < (int)a; ++i)
#define rrep(i, a) for (int i = (int)a - 1; i >= 0; --i)
#define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i)
#define RREP(i, a, b) for (int i = (int)a - 1; i >= b; --i)
#define repl(i, a) for (ll i = (ll)0; i < (ll)a; ++i)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define popcount __builtin_popcount
#define popcountll __builtin_popcountll
#define fi first
#define se second
using ll = long long;
constexpr ll mod = 1e9 + 7;
constexpr ll mod_998244353 = 998244353;
constexpr ll INF = 1LL << 60;

// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")

//using lll=boost::multiprecision::cpp_int;
//using Double=boost::multiprecision::number<boost::multiprecision::cpp_dec_float<128>>;//仮数部が1024桁
template <class T>
inline bool chmin(T &a, T b)
{
	if (a > b)
	{
		a = b;
		return true;
	}
	return false;
}
template <class T>
inline bool chmax(T &a, T b)
{
	if (a < b)
	{
		a = b;
		return true;
	}
	return false;
}

template <typename T>
T mypow(T x, T n, const T &p = -1)
{ //x^nをmodで割った余り

	if (p != -1)
	{
		x =(x%p+p)%p;
	}
	T ret = 1;
	while (n > 0)
	{
		if (n & 1)
		{
			if (p != -1)
				ret = (ret * x) % p;
			else
				ret *= x;
		}
		if (p != -1)
			x = (x * x) % p;
		else
			x *= x;
		n >>= 1;
	}
	return ret;
}

using namespace std;
//using namespace atcoder;

template<typename T>
struct BIT{
  //0オリジンで与える
  vector<T>bit;
  int N;

  BIT(int n):N(n){
    bit.assign(++n,0);
  }

  T sum(int i){
    T s=0;
    ++i;//0オリジンに対応させる
    while(i>0){
      s+=bit[i];
      i-=i&-i;//iから最後の1のビットを減算
    }
    return s;
  }

  void add(int i,T x){
    ++i;//0オリジンに対応させる
    while(i<(int)bit.size()){
      bit[i]+=x;
      i+=i&-i;
    }
  }

  T Lower_bound(T k){
    if(k<=0)
      return 0;
    T x = 0;
    T mul = 1;
    while (mul<N){
      mul *= 2;
    }
    for (T i = mul; i > 0;i/=2){
      if(x+i<=N&&bit[x+i]<k){
        k -= bit[x + i];
        x += i;
      }
    }
    return x;
  }
};


void solve()
{	
 int n;
 cin>>n;
 vector<vector<int>>g(n);
 rep(i,n-1){
	 int a;
	 cin>>a;
	 g[i+1].eb(a);
	 g[a].eb(i+1);
 }
 BIT<int>bit(n+5);
 ll ans=0;
 auto dfs=[&](auto self,int v,int p=-1)->void{
	 ans+=bit.sum(v);
	 bit.add(v,1);
	 for(auto x:g[v]){
		 if(x!=p){
			self(self,x,v);
		 }
	 }
	 bit.add(v,-1);
	 return;
 };
 dfs(dfs,0);
 cout<<ans<<"\n";
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout << fixed << setprecision(15);
	solve();
	return 0;
}