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

using ll=long long;

#define rng(i,a,b) for(int i=int(a);i<int(b);i++)
#define rep(i,b) rng(i,0,b)
#define gnr(i,a,b) for(int i=int(b)-1;i>=int(a);i--)
#define per(i,b) gnr(i,0,b)
#define pb push_back
#define eb emplace_back
#define a first
#define b second
#define bg begin()
#define ed end()
#define all(x) x.bg,x.ed
#define si(x) int(x.size())
#ifdef LOCAL
#define dmp(x) cerr<<__LINE__<<" "<<#x<<" "<<x<<endl
#else
#define dmp(x) void(0)
#endif

template<class t,class u> bool chmax(t&a,u b){if(a<b){a=b;return true;}else return false;}
template<class t,class u> bool chmin(t&a,u b){if(b<a){a=b;return true;}else return false;}

template<class t> using vc=vector<t>;
template<class t> using vvc=vc<vc<t>>;

using P=pair<int,int>;
using vi=vc<int>;


void solve(){
	int n,x;
	cin>>n>>x;
	vc<int> A(n);
	for(int i=0;i<n;i++) cin>>A[i];
	int ret=0;
	vc<int> dist(n);
	for(int i=0;i<n;i++) dist[i]=n+1;
	queue <int> que;
	if(A[0]!=0){
		dist[A[0]]=1;
		que.push(A[0]);
	} else{
		dist[1]=2;
		que.push(1);
	}
	while(!que.empty()){
		int v=que.front();que.pop();
		if(v+1<n&&dist[v+1]>dist[v]+1){
			dist[v+1]=dist[v]+1;
			que.push(v+1);
		}
		if(dist[A[v]]>dist[v]+1){
			dist[A[v]]=dist[v]+1;
			que.push(A[v]);
		}
	}
	cout<<dist[x]<<endl;
}
int main(){
	cin.tie(0);
	ios::sync_with_stdio(0);
	cout<<fixed<<setprecision(20);
	int T=1;
	while(T--) solve();
}