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

#define rep(i,n) for(int i = 0; i < (int)n; i++)
#define FOR(n) for(int i = 0; i < (int)n; i++)
#define repi(i,a,b) for(int i = (int)a; i < (int)b; i++)
#define pb push_back
#define m0(x) memset(x,0,sizeof(x))
#define fill(x,y) memset(x,y,sizeof(x))
#define bg begin()
#define ed end()
#define all(x) x.bg,x.ed
//#define mp make_pair
#define vi vector<int>
#define vvi vector<vi>
#define vll vector<ll>
#define vvll vector<vll>
#define vs vector<string>
#define vvs vector<vs>
#define vc vector<char>
#define vvc vector<vc>
#define pii pair<int,int>
#define pllll pair<ll,ll>
#define vpii vector<pair<int,int>>
#define vpllll vector<pair<ll,ll>>
#define vpis vector<pair<int,string>>
#define vplls vector<pair<ll, string>>
#define vpsi vector<pair<string, int>>
#define vpsll vector<pair<string, ll>>

template<typename T>
void chmax(T &a, const T &b) {a = (a > b? a : b);}
template<typename T>
void chmin(T &a, const T &b) {a = (a < b? a : b);}

using ll = long long;
using ld = long double;
using ull = unsigned long long;

const ll INF = numeric_limits<long long>::max() / 2;
const ld pi = 3.1415926535897932384626433832795028;
const ll mod = 1e9 + 7;
int dx[] = {-1, 0, 1, 0, -1, -1, 1, 1};
int dy[] = {0, -1, 0, 1, -1, 1, -1, 1};

#define int long long

vector<int> dijkstra(vector<vector<pair<int, int>>> &graph, int start) {
    int n = (int)graph.size();
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
    vector<int> dist(n, INF);
    dist[start] = 0;
    pq.emplace(dist[start], start);
    while(!pq.empty()) {
        pair<int, int> p = pq.top();
        pq.pop();
        int v = p.second;
        if(dist[v] < p.first) continue;
        for(auto e : graph[v]) {
            if(dist[e.first] > dist[v] + e.second) {
                dist[e.first] = dist[v] + e.second;
                pq.emplace(dist[e.first], e.first);
            }
        }
    }
    return dist;
}

void solve() {
    int n;
    cin >> n;
    vector<vpii> g(n);
    FOR(n - 1) {
        int r;
        cin >> r;
        r--;
        g[i].emplace_back(r, 1);
    }
    FOR(n - 1) g[i + 1].emplace_back(i, 0);
    cout << dijkstra(g, 0)[n - 1] << endl;
}

signed main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    solve();
    return 0;
}