#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define FORR(i,a,b) for(int i=(a);i>=(b);i--)
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define pcnt __builtin_popcount
#define sz(x) (int)(x).size()
#define maxs(x,y) x=max(x,y)
#define mins(x,y) x=min(x,y)
#define show(x) cout<<#x<<" = "<<x<<endl;
#define all(a) (a.begin()),(a.end())
#define each(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();it++)
#define perm(c) sort(all(c));for(bool c##p=1;c##p;c##p=next_permutation(all(c)))
#define bit(n) (1LL<<(n))
#define randInt(l,r) (uniform_int_distribution<ll>(l,r)(rnd))
#define randDouble(l,r) (uniform_real_distribution<double>(l,r)(rnd))

typedef long long ll;
typedef __int128_t lll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
template<class T>using V=vector<T>;
template<class T>using VV=V<V<T>>;
template<class T,class Y>ostream& operator<<(ostream& o,const pair<T,Y>& p){return o<<"("<<p.fi<<", "<<p.se<<")";}
template<typename A,size_t N,typename T>void Fill(A (&array)[N],const T&v){fill((T*)array,(T*)(array+N),v);}
lll gcd(lll a,lll b,lll &x,lll &y){if(!b){x=1;y=0;return a;}lll d=gcd(b,a%b,y,x);y-=a/b*x;return d;}
ll gcd(ll a,ll b){lll x=0,y=0;return gcd(a,b,x,y);}
ll modPow(lll a,lll n,ll m){if(!a)return a;lll p=1;for(;n>0;n>>=1,a=a*a%m)if(n&1)p=p*a%m;return(ll)p;}
bool isPrime(ll n){if(n<2||n%2==0)return n==2;lll t=n-1,d=t/(t&-t);for(lll a:{2,325,9375,28178,450775,9780504,1795265022})if(a%n){for(t=d,a=modPow(a,t,n);t!=n-1&&a!=1&&a!=n-1;a=a*a%n,t=t*2%n);if(a!=n-1&&t%2==0)return 0;}return 1;}
void dout(double d){printf("%.12f\n",d);}
const int IINF = 1e9+6;
const ll LINF = 1e18;
const int MOD = 1e9+7;
const double PI = acos(-1);
const double EPS = 1e-10;
static random_device rd;
static mt19937 rnd(rd());

const int N = 2e5;

struct Seg{
  typedef ll T;
  const T e = 0ll;
  inline T m(const T&a, const T&b){return a+b;}
//###################################################
  typedef int i;i n;vector<T> d;
  T q(i a,i b,i k,i l,i r){return (r<=a||b<=l)?e:(a<=l&&r<=b)?d[k]:m(q(a,b,k*2+1,l,(l+r)/2),q(a,b,k*2+2,(l+r)/2,r));}

  void init(i m){n=1<<(32-__builtin_clz(m-1));d.resize(2*n-1);for(int i=0;i<2*n-1;i++)d[i]=e;}
  void init(vector<T>&v){init(v.size());for(int j=0;j<v.size();j++)d[j+n-1]=v[j];for(int k=n-2;k>=0;k--)d[k]=m(d[k*2+1],d[k*2+2]);}
  void update(i k,T a){k+=n-1;d[k]=a;while(k>0){k=(k-1)/2;d[k]=m(d[k*2+1],d[k*2+2]);}}
  T query(i a,i b){return q(a,b,0,0,n);}
  T get(i a){return d[n+a-1];}
} seg;

int n;
ll ans;
V<int> e[N];

void dfs(int a){
  seg.update(a, 1);
  ans += seg.query(0, a);
  for(int b:e[a]) dfs(b);
  seg.update(a, 0);
}

main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> n;
  FOR(i, 1, n){
    int a;
    cin >> a;
    e[a].pb(i);
  }
  seg.init(n);
  dfs(0);
  cout << ans << endl;
}