#include <bits/stdc++.h>
#define endl '\n'
#define int long long
#define lint long long
#define pii pair<int,int>
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define SZ(v) ((int)v.size())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
#define MINF(a) memset(a,0x3f,sizeof(a))
#define POW(n) (1LL<<(n))
#define POPCNT(n) (__builtin_popcount(n))
#define IN(i,a,b) (a <= i && i <= b)
using namespace std;
template <typename T> inline bool CHMIN(T& a,T b) { if(a>b) { a=b; return 1; } return 0; }
template <typename T> inline bool CHMAX(T& a,T b) { if(a<b) { a=b; return 1; } return 0; }
template <typename T> inline void SORT(T& a) { sort(ALL(a)); }
template <typename T> inline void REV(T& a) { reverse(ALL(a)); }
template <typename T> inline void UNI(T& a) { sort(ALL(a)); a.erase(unique(ALL(a)),a.end()); }
template <typename T> inline T LB(vector<T>& v, T a) { return *lower_bound(ALL(v),a); }
template <typename T> inline int LBP(vector<T>& v, T a) { return lower_bound(ALL(v),a) - v.begin(); }
template <typename T> inline T UB(vector<T>& v, T a) { return *upper_bound(ALL(v),a); }
template <typename T> inline int UBP(vector<T>& v, T a) { return upper_bound(ALL(v),a) - v.begin(); }
template <typename T1, typename T2> ostream& operator<< (ostream& os, const pair<T1,T2>& p) { os << p.first << " " << p.second; return os; }
template <typename T1, typename T2> istream& operator>> (istream& is, pair<T1,T2>& p) { is >> p.first >> p.second; return is; }
template <typename T> ostream& operator<< (ostream& os, const vector<T>& v) { REP(i,v.size()) { if (i) os << " "; os << v[i]; } return os; }
template <typename T> istream& operator>> (istream& is, vector<T>& v) { for(T& in : v) is >> in; return is; }
template <typename T = int> vector<T> make_v(size_t a) { return vector<T>(a); }
template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts) { return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...)); }
template <typename T, typename V> typename enable_if<is_class<T>::value == 0>::type fill_v(T &t, const V &v) { t = v; }
template <typename T, typename V> typename enable_if<is_class<T>::value != 0>::type fill_v(T &t, const V &v) { for(auto &e : t) fill_v(e,v); }
const lint MOD = 1000000007;
const lint INF = 0x3f3f3f3f3f3f3f3f;
const double EPS = 1e-10;

struct LowestCommonAncestorDoubling {
    using UnweightedGraph = vector<vector<int>>;
    const UnweightedGraph &g;
    vector<vector<int>> parent;
    vector<int> depth;

    LowestCommonAncestorDoubling(const UnweightedGraph &g, int root = 0) : g(g)
    {
        build(root);
    }

    void dfs(int v, int p, int d) {
        parent[0][v] = p;
        depth[v] = d;
        for (int u : g[v]) if (u != p) {
            dfs(u, v, d + 1);
        }
    }

    // 前処理
    void build(int root = 0) {
        const int n = g.size();
        int h = 1;
        while ((1 << h) < n) ++ h;
        parent.assign(h, vector<int>(n, -1));
        depth.assign(n, -1);
        dfs(root, -1, 0);
        for (int i = 0; i + 1 < h; ++i) {
            for (int v = 0; v < n; ++v) {
                if (parent[i][v] != -1)
                    parent[i + 1][v] = parent[i][parent[i][v]];
            }
        }
    }

    // uとvのLCAを計算
    int lca(int u, int v) {
        if (depth[u] > depth[v]) swap(u, v);
        for (int i = 0; i < (int)parent.size(); ++i) {
            if ((depth[v] - depth[u]) >> i & 1)
                v = parent[i][v];
        }
        if (u == v) return u;
        for (int i = (int)parent.size() - 1; i >= 0; --i) {
            if (parent[i][u] != parent[i][v]) {
                u = parent[i][u];
                v = parent[i][v];
            }
        }
        return parent[0][u];
    }

    // u-v間の距離
    int dist(int u, int v) {
        int w = lca(u, v);
        return abs(depth[u] - depth[w]) + abs(depth[v] - depth[w]);
    }
};
using LCA = LowestCommonAncestorDoubling;

void _main() {
    int n;
    cin >> n;
    vector<vector<int>> g(n);
    vector<int> p(n, -1);
    REP(i, n - 1) {
        cin >> p[i + 1];
        p[i + 1]--;
        g[i + 1].push_back(p[i + 1]);
        g[p[i + 1]].push_back(i + 1);
    }
    vector<int> depth(n, -1);
    queue<int> que;
    depth[0] = 0;
    que.push(0);
    while (!que.empty()) {
        int v = que.front(); que.pop();
        for (int u : g[v]) if (depth[u] < 0) {
            depth[u] = depth[v] + 1;
            que.push(u);
        }
    }

    const int max_depth = *max_element(ALL(depth));
    vector<vector<int>> depth_list(max_depth + 1);
    vector<int> time(n, -1), ord = {0};
    REP(i, n) depth_list[depth[i]].push_back(i);
    assert(depth_list[0].size() == 1 && depth_list[0][0] == 0);
    REP(i, max_depth) {
        sort(ALL(depth_list[i + 1]), [&](int a, int b) {
            if (p[a] != p[b]) return time[p[a]] < time[p[b]];
            return a < b;
        });
        REP(j, SZ(depth_list[i + 1])) {
            time[depth_list[i + 1][j]] = j;
            ord.push_back(depth_list[i + 1][j]);
        }
    }
    LCA lca(g);
    int ans = 0;
    REP(i, n - 1) {
        ans += lca.dist(ord[i], ord[i + 1]);
    }
    cout << ans << endl;
}

signed main(signed argc, char **argv) {
    if (argc > 1) {
        if (strchr(argv[1], 'i'))
            freopen("input.txt", "r", stdin);
        if (strchr(argv[1], 'o'))
            freopen("output.txt", "w", stdout);
    }
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    _main();
    return 0;
}


Measured memory_bytes: 34716