#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i< (n); ++i)
#define repi(i, a, b) for (int i = (a); i < (b); ++i)
#define all(x) (x).begin(), (x).end()
#define fore(i, a) for(auto &i:a)
using ll = long long;
#include<atcoder/segtree>
using namespace atcoder;
struct S{
	ll value;
};
S op(S a, S b){
	return S{a.value+b.value};
}
S e(){
	return S{0};
}

int main() {
	ll n; cin >> n;
  segtree<S, op, e> seg(2*n);	
	vector<vector<ll>> ch(n);
	ll a;
	rep(i, n-1){
		cin >> a;
		ch[a].push_back(i+1);
	}
	vector<ll> pre(n), post(n);
	ll cnt = 0;
	function<void(ll)> dfs = [&](ll x){
    pre[x] = cnt;
		cnt++;
		fore(i, ch[x]){
			dfs(i);
		}
		post[x] = cnt;
		cnt++;
	};
	dfs(0);
	ll ans = 0;
	for(ll i=n-1;i>=0;i--){
		ans += seg.prod(pre[i], post[i]+1).value;

		seg.set(pre[i], {1});
	}
	cout << ans << endl;


}