#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
//using mint = static_modint<998244353>;
//using mint = modint;
using mint = static_modint<1000000007>;
using vm = vector<mint>;
using vvm = vector<vm>;
ostream &operator<<(ostream &o,const mint &m){cout<<m.val();return o;}
using ll = long long;
using vl = vector<ll>;
using vvl = vector<vl>;
using pl = pair<ll,ll>;
#define rep(i,n) for(ll i=0;i<(ll)(n);++i)
#define reps(i,s,n) for(ll i=(s);i<(ll)(n);++i)
#define rep1(i,n) for(ll i=1;i<=(ll)(n);++i)
#define chmin(x,y) x=min(x,y)
#define chmax(x,y) x=max(x,y)
const long long INF = 1e18;

#ifdef DEBUG
#include <debug.hpp>
#endif

int main(){
#ifdef DEBUG
	cout << "--- Input ---" << endl;
#endif
	ll N;cin>>N;
	vvl g(N);
	reps(v,1,N){
		ll u;cin>>u;
		g.at(u).push_back(v);
		g.at(v).push_back(u);
	}
	fenwick_tree<ll> bit(N);
	ll ans=0;

	auto rec=[&](auto f,ll u,ll p=-1)->void{
#ifdef DEBUG
		cout<<"u="<<u<<" p="<<p<<endl;
#endif
		assert(u>=0&&u<N);
		ans+=bit.sum(0,u);
		bit.add(u,1);
		rep(v,g.at(u).size()){
			if(g.at(u).at(v)==p)continue;
			f(f,g.at(u).at(v),u);
		}
		bit.add(u,-1);
	};
#ifdef DEBUG
	cout<<g;
	cout << "--- Logic ---" << endl;
#endif
	rec(rec,0);	

#ifdef DEBUG
	cout << "--- Answer ---" << endl;
#endif
	cout<<ans<<endl;
	return 0;
}
//cout << fixed << setprecision(9);