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

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl
#define p_yes() p("Yes")
#define p_no() p("No")

const ll mod = 1e9 + 7;
const ll inf = 1e18;

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;
  }
};

auto bit = BinaryIndexedTree<ll>(200010);
ll cnt = 0;
vector<ll> G[200010];

void dfs(ll i){
    // iより値の小さい先祖
    cnt += bit.sum(i-1);

    // 自身を先祖に足す
    bit.add(i, 1);

    // 子どもたち
    for(ll to : G[i]){
        dfs(to);
    }

    // 自身を先祖一覧から取り除く
    bit.add(i, -1);
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    ll N;
    cin >> N;

    FOR(i, 1, N){
        ll parent; cin >> parent;
        G[parent].push_back(i);
    }

    dfs(0);
    p(cnt);
    
    return 0;
}