#include<bits/stdc++.h>
using namespace std;
const int N=200;
struct node{
	int f,cnt;
}; 
node q[N+10],now;
int n,a,b,k[N+10],h,t,vis[N+20],nxtf,flag;
void bfs(int a,int b){
	h=t=1;
	q[t++]=(node){a,0};
	vis[a]=1;
	flag=0;
	while(h<t)
	{
		now.f=a;
		if(now.f==b){cout<<now.cnt;flag=1;return;}
		nxtf=now.f+k[now.f];
		if(now.f>0&&now.f<=n&&vis[now.f]==0) 
		{
		q[t++]=(node){nxtf,now.cnt++};
		vis[nxtf]=1;
		}
		nxtf=now.f-k[now.f];
		if(now.f>0&&now.f<=n&&vis[now.f]==0)
		{
			q[t++]=(node){nxtf,now.cnt++};
			vis[nxtf]=1;
		}
	}
}
int main(){
	cin>>n>>a>>b;
	for(int i=1;i<=n;i++) cin>>k[i];
	bfs(a,b);
	if(flag!=0) cout<<now.cnt;
	else cout<<-1;
	return 0;
}