/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2020.06.11 17:38:04
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;



template< typename T >
struct BinaryIndexedTree {
    std::vector< T > data;
    BinaryIndexedTree() {}
    BinaryIndexedTree(int sz) {
        data.assign(++sz, 0);
    }
    
    inline T sum(int k) {
        T ret = 0;
        for (++k; k > 0; k -= k & -k) ret += data[k];
        return (ret);
    }
    
    inline T sum(int left, int right) {
        return sum(right) - sum(left - 1);
    }
    
    
    inline void add(int k, T x) {
        for (++k; k < data.size(); k += k & -k) data[k] += x;
    }
    
    
    
    int get(ll k) {
        ++k;
        int res = 0;
        int N = 1; while (N < (int)data.size()) N *= 2;
        for (int i = N / 2; i > 0; i /= 2) {
            if (res + i < (int)data.size() && data[res + i] < k) {
                k = k - data[res + i];
                res = res + i;
            }
        }
        return res + 1;
    }
    void print() {
        std::cout << "[ ";
        for (int i = 0; i < data.size() - 1; i++) {
            std::cout << sum(i, i);
            if (i < data.size() - 2) cout << ", ";
        }
        std::cout << " ]" << endl;
    }
};
vector<vector<int>> g;
ll ans;
BinaryIndexedTree<int> bit;
int n;
void dfs(int v, int p = -1) {
    ll tmp = bit.sum(v+1,n-1);
    bit.add(v,1);
    for(int u : g[v]) {
        if (p == u) continue;
        dfs(u,v);
    }
    ans += bit.sum(v+1,n-1) - tmp;
}
int main() {
    cin >> n;
    g.resize(n);
    bit = BinaryIndexedTree<int>(n);
    for (int i = 0; i < n-1; i++) {
        int a;cin >> a;
        g[a].push_back(i+1);
        g[i+1].push_back(a);
    }
    dfs(0);
    cout << ans << endl;
    return 0;
}