#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
//using mint = modint1000000007;
typedef long long ll;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> T;
template<typename T>bool chmax(T& a, const T& b) { if (a < b) { a = b;return true; } else { return false; } }
template<typename T>bool chmin(T& a, const T& b) { if (a > b) { a = b;return true; } else { return false; } }

const int di[] = { -1,0,1,0 };
const int dj[] = { 0,-1,0,1 };
const long long INF = 9223372036854775807;
const int inf = 1001001001;

int op(int a, int b) { return a + b; }

int e() { return 0; }
int main(void) {
    int n; cin >> n;
    vector<vector<int>> g(n);
    for (int i = 0; i < n - 1; i++) {
        int a; cin >> a;
        g[a].push_back(i + 1);
    }
    segtree<int, op, e> seg(n);
    ll ans = 0;
    auto dfs = [&](auto dfs, int pos)->void {
        //cout << pos << "\n";
        ans += seg.prod(0, pos);
        seg.set(pos, 1);
        for (auto x : g[pos]) {
            dfs(dfs, x);
            //seg.set(x, 0);
        }
        seg.set(pos, 0);
        };
    dfs(dfs, 0);
    cout << ans << "\n";
}
//overflow,out_of_range