#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
struct Edge {
	int to, cost;
	Edge(int _to, int _cost) :to(_to), cost(_cost) {}
};
vector<Edge>g[200005];
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n; cin >> n;
	rep(i, n - 1) {
		int r; cin >> r; r--;
		g[i].emplace_back(r, 1);
	}
	rep(i, n - 1)g[i + 1].emplace_back(i, 0);
	deque<int> q;
	vector<int> d(n, INF);
	d[0] = 0;
	q.push_back(0);
	while (!q.empty()) {
		int v = q.front();
		q.pop_front();
		for (auto e : g[v]) {
			int pos = e.to;
			int cost = e.cost;
			if (0 == cost) {
				if (chmin(d[pos], d[v]))q.push_front(pos);
			}
			else {
				if (chmin(d[pos], d[v] + 1))q.push_back(pos);
			}
		}
	}
	cout << d[n - 1] << endl;
	return 0;
}