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

struct Edge
{
	int to; // 辺の行先
	int weight; // 辺の重み
	Edge(int t, int w) : to(t), weight(w){} 
};
using Graph = vector<vector<Edge>>;

int main()
{
	int N;
	cin >> N;
	int R;
	Graph G(N);
	for(int i = 0; i < N - 1; i++)
	{
		cin >> R;
		R--;
		G[i].push_back(Edge(R, 1));
	}
	for(int i = 0; i < N - 1; i++) G[i + 1].push_back(Edge(i, 0));
	
	int inf = 100000001;
	deque<int> dq;
	dq.push_back(0);
	vector<int> dist(N, inf);
	dist[0] = 0;
	while(!dq.empty())
	{
		int p = dq.front();
		dq.pop_front();
		
		for(Edge e : G[p])
		{
			if(dist[p] + e.weight < dist[e.to])
			{
				dist[e.to] = dist[p] + e.weight;
				if(e.weight == 0) dq.push_front(e.to);
				else dq.push_back(e.to);
			}
		}
	}
	
	cout << dist[N - 1] << endl;
	return 0;
}