#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll = long long;
using vi = vector<int>;
using vvi = vector<vector<int>>;
using pii = pair<int, int>;
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define repr(i, n) for (int i = (int)(n - 1); i >= 0; --i)

int main() {
    const int INF = 1001001001;
    int n;
    cin >> n;
    vector<vector<pii>> g(n, vector<pii>(0));
    rep(i, n - 1) g[i + 1].emplace_back(i, 0);
    rep(i, n - 1) {
        int r;
        cin >> r;
        r--;
        g[i].emplace_back(r, 1);
    }

    vi ret(n, INF);
    deque<pii> dq;
    dq.emplace_back(0, 0);
    ret[0] = 0;
    while (dq.size()) {
        int v, d;
        tie(v, d) = dq.front();
        dq.pop_front();
        if (d > ret[v]) continue;
        for (auto [t, c] : g[v]) {
            if (d + c < ret[t]) {
                ret[t] = d + c;
                if (c == 0) {
                    dq.emplace_front(t, d);
                } else {
                    dq.emplace_back(t, d + c);
                }
            }
        }
    }
    cout << ret[n - 1] << endl;
    return 0;
}