#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll=long long;
using ld=long double;
ld pie=3.141592653589793;
ll inf=144499999999994;
ll mod=1000000007;
ll op(ll a,ll b){
    return a+b;
}
ll e(){
    return 0;
}
ll ans=0;
void dfs(ll now,segtree<ll,op,e>&seg,vector<vector<ll>>&g,vector<ll>&memo){
    memo[now]=1;
    ans+=seg.prod(0,now);
    seg.set(now,1);
    for (ll i = 0; i < g[now].size(); i++)
    {
        if (memo[g[now][i]]==0)
        {
            dfs(g[now][i],seg,g,memo);
        }
    }
    seg.set(now,0);
}
int main(){
    ll n;
    cin >> n;
    vector<ll>a(n);
    vector<vector<ll>>g(n);
    for (ll i = 0; i < n-1; i++)
    {
        cin >> a[i];
        g[a[i]].push_back(i+1);
    }
    vector<ll>memo(n+10,0);
    segtree<ll,op,e>seg(memo);
    dfs(0,seg,g,memo);
    cout << ans << endl;
}