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

// #define int long long
#define rep(i, n) for (long long i = (long long)(0); i < (long long)(n); ++i)
#define reps(i, n) for (long long i = (long long)(1); i <= (long long)(n); ++i)
#define rrep(i, n) for (long long i = ((long long)(n)-1); i >= 0; i--)
#define rreps(i, n) for (long long i = ((long long)(n)); i > 0; i--)
#define irep(i, m, n) for (long long i = (long long)(m); i < (long long)(n); ++i)
#define ireps(i, m, n) for (long long i = (long long)(m); i <= (long long)(n); ++i)
#define irreps(i, m, n) for (long long i = ((long long)(n)-1); i > (long long)(m); ++i)
#define SORT(v, n) sort(v, v + n);
#define REVERSE(v, n) reverse(v, v+n);
#define vsort(v) sort(v.begin(), v.end());
#define all(v) v.begin(), v.end()
#define mp(n, m) make_pair(n, m);
#define cinline(n) getline(cin,n);
#define replace_all(s, b, a) replace(s.begin(),s.end(), b, a);
#define PI (acos(-1))
#define FILL(v, n, x) fill(v, v + n, x);
#define sz(x) (long long)(x.size())

using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vs = vector<string>;
using vpll = vector<pair<ll, ll>>;
using vtp = vector<tuple<ll,ll,ll>>;
using vb = vector<bool>;

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

template<class t> using vc=vector<t>;
template<class t> using vvc=vc<vc<t>>;

const ll INF = 1e9+10;
const ll MOD = 1e9+7;
const ll LINF = 1e18;

/**
 * Binary Index Tree
 * パラメータの添え字は全て1-indexである点に注意する
 */
template<typename T>
class BIT {
  private:
  int n;
  vector<T> d;
  
  public:
  BIT(int n=0):n(n),d(n+1) {}
  
  /// i以降の累積和にxを加算
  void add(int i, T x=1) {
    for (; i <= n; i += i&-i) {
      d[i] += x;
    }
  }
  
  /// 閉区間[1,i]の累積和を求める
  T sum(int i) {
    T x = 0;
    for (; i; i -= i&-i) {
      x += d[i];
    }
    return x;
  }
  
  /// 閉区間[l,r]の累積和を求める
  T sum(int l, int r) {
    return sum(r) - sum(l-1);
  }
};

const ll maxn=200100;
auto bit=BIT<ll>(maxn);

vll G[200100];

ll ans=0;
void dfs(ll v, ll p){
  ans+=bit.sum(v+1);
  bit.add(v+1);
  for(auto nv: G[v]){
    if(nv==p) continue;
    dfs(nv,v);
  }
  bit.add(v+1,-1);
}


signed main()
{
  cin.tie( 0 ); ios::sync_with_stdio( false );
  
  ll n; cin>>n;
  irep(i,1,n){
    ll a; cin>>a;
    G[i].push_back(a);
    G[a].push_back(i);
  }
  dfs(0,-1);
  cout<<ans<<endl;
  
}