#include<bits/stdc++.h>
using namespace std;
const int M = 1000000007;

vector<vector<int>> edge;
set<int> se;

long long dfs(int p, int par) {
    long long ret = distance(se.begin(), se.lower_bound(p));
    se.insert(p);
    for (auto& i : edge[p]) {
        if (i == par) continue;
        ret += dfs(i, p);
    }
    se.erase(p);
    return ret;
}

int main() {
    int n;
    cin >> n;
    edge = vector<vector<int>>(n);
    for (int i = 1; i < n; ++i) {
        int a;
        cin >> a;
        edge[i].push_back(a);
        edge[a].push_back(i);
    }
    cout << dfs(0, -1) << "\n";
    return 0;
}