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

// SegmentTree on range sum, single value modification.
template<typename T>
class SegTreeSum{
    size_t n;
    vector<T> data;
public:
    SegTreeSum(size_t _n): n(_n), data(2 * _n, 0) {}
    void modify(size_t i, T v){   // set value at index i to v.
        for (data[i += n] = v; i > 1; i >>= 1) data[i>>1] = data[i] + data[i^1];
    }
    T query(size_t L, size_t R){  // sum on interval [L, R)
        T ret = 0;
        for (L += n, R += n; L < R; L >>= 1, R >>= 1){
            if (L & 1) ret += data[L++];
            if (R & 1) ret += data[--R];
        }
        return ret;
    }
};

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N;
    cin >> N;
    vector<vector<int>> Es(N, vector<int>());
    for (int i = 1; i < N; ++i) {
        int v;
        cin >> v;
        Es[v].push_back(i);
    }
    long long count = 0;
    SegTreeSum<int> seg(N);
    vector<int> que = {0};
    vector<int> visited(N, 0);
    while (que.size() >= 1){
        int v = que.back();
        if (visited[v]){
            que.pop_back();
            seg.modify(v, 0);
            continue;
        }
        visited[v] = 1;
        count += seg.query(0, v);
        seg.modify(v, 1);
        for (auto u : Es[v]){
            que.push_back(u);
        }
    }
    cout << count << endl;
    return 0;
}