#include<bits/stdc++.h>
using namespace std;
#include <unordered_set>
#include <random>
//#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
//#define vec vector<ll>
//#define mat vector<vector<ll> >
#define fi first
#define se second
#define double long double
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
//typedef long double ld;
typedef complex<double> Complex;
const ll INF=1e9+7;
const ll MOD=998244353;
const ll inf=INF*INF;
const ll mod=INF;
const ll MAX=200010;
const double PI=acos(-1.0);
typedef vector<vector<ll> > mat;
typedef vector<ll> vec;


//dijkstra(O(ElogV))
//0-indexed
void dijkstra(ll n,ll s,vector<vector<pll> >&G,vector<ll> &d){
    priority_queue<pll,vector<pll>,greater<pll> >pq;
    rep(i,n){
        d[i]=inf;
    }
    d[s]=0;
    pq.push(mp(0,s));
    while(!pq.empty()){
        pll k=pq.top();pq.pop();
        ll v=k.second;
        if(d[v]<k.first)continue;
        for(auto e:G[v]){
            if(d[e.first]>d[v]+e.second){
                d[e.first]=d[v]+e.second;
                pq.push(mp(d[e.first],e.first));
            }
        }
    }
}


void solve(){
    ll n;cin>>n;
    vector<ll>r(n);
    vector<vector<pll> >G(n);
    rep(i,n-1){
        cin>>r[i];
        r[i]--;
    }
    rep(i,n-1){
        G[i+1].pb(mp(i,0));
    }
    rep(i,n){
        G[i].pb(mp(r[i],1));
    }
    vector<ll>d(n);
    dijkstra(n,0,G,d);
    cout<<d[n-1]<<endl;
}

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