use std::{cmp::Reverse, collections::BinaryHeap};

const INF: usize = 1usize << 60;

#[derive(Debug, Clone)]
struct Dijkstra {
    n: usize,
    pathcosts: Vec<Vec<(usize, usize)>>,
    pathcostsrev: Vec<Vec<(usize, usize)>>,
    costs: Vec<usize>
}

impl Dijkstra {
    fn new(n: usize) -> Self {
        Self {
              n: n
            , pathcosts: vec![vec![]; n]
            , pathcostsrev: vec![vec![]; n]
            , costs: vec![INF; n]
        }
    }

    fn pusha2b(&mut self, a: usize, b: usize, cost: usize) {
        self.pathcosts[a].push((cost, b));
        self.pathcostsrev[b].push((cost, a));
    }

    fn get_cost(&self, idx: usize) -> usize {
        self.costs[idx]
    }

    fn solve(&mut self, startpoint: usize) {
        let mut que = BinaryHeap::new();
        que.push(Reverse((0, startpoint)));
        self.costs[startpoint] = 0;
        while let Some(Reverse(p)) = que.pop() {
            let cost = p.0;
            let dest = p.1;
            if cost > self.costs[dest] { continue; }
            for &p2 in self.pathcosts[dest].iter() {
                if self.costs[dest] + p2.0 < self.costs[p2.1] {
                    self.costs[p2.1] = self.costs[dest] + p2.0;
                    que.push(Reverse((self.costs[p2.1], p2.1)));
                }
            }
        }
    }

    fn reconstruct(&self, startpoint: usize, endpoint: usize) -> Vec<(usize, usize)> {
        let mut ret = vec![];
        if self.costs[endpoint] == INF { return ret; }
        let mut current = endpoint;
        while current != startpoint {
            for &(cost, u) in self.pathcostsrev[current].iter() {
                if self.costs[current] == self.costs[u] + cost {
                    let prev = current;
                    current = u;
                    ret.push((current, prev));
                    break;
                }
            }
        }
        ret.reverse();
        ret
    }
}

fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();
    let mut r = String::new();
    std::io::stdin().read_line(&mut r).ok();
    let r: Vec<usize> = r.trim().split_whitespace().map(|s| s.parse::<usize>().unwrap()-1).collect();

    let mut dijkstra = Dijkstra::new(n);
    for i in 0..n-1 {
        dijkstra.pusha2b(i, r[i], 1);
        dijkstra.pusha2b(i+1, i, 0);
    }
    dijkstra.solve(0);
    println!("{}", dijkstra.get_cost(n-1));
}