#include <bits/stdc++.h>

using namespace std;

constexpr int INF = 1e9;
struct edge {
    int to, cost;
};
bool chmin(int& a, int b) {
    return a > b ? a = b, true : false;
}

int main() {
    int N; cin >> N;

    vector<vector<edge>> G(N);
    for (int i = 0; i < N - 1; ++i) {
        int a; cin >> a;
        G[i].push_back({a - 1, 1});
    }
    for (int i = 1; i < N; ++i) G[i].push_back({i - 1, 0});

    vector<int> dist(N, INF); dist[0] = 0;
    deque<int> que; que.push_back(0);
    while (!que.empty()) {
        int v = que.front(); que.pop_front();
        for (edge e : G[v]) {
            if (chmin(dist[e.to], dist[v] + e.cost)) {
                if (e.cost == 1) que.push_back(e.to);
                else que.push_front(e.to);
            }
        }
    }
    cout << dist[N - 1] << endl;
}