#include<iostream>
#include<queue>
#include<string.h>
using namespace std;
int main()
{
	int N,A,B;
	cin>>N>>A>>B;
	
	int k[1001];
	for(int i=1;i<=N;i++)
	{
		cin>>k[i];
	}
	
	queue<int> q;
	int a[101]; //ÓÃÀ´´¢´æ°´¼ü´ÎÊý
	memset(a,-1,sizeof(a));
	
	a[A]=0;
	int tmp=A;
	q.push(tmp);
	
	while(!q.empty()) 
	{
		int u=q.front();
		q.pop();
		
		if((u+k[u]>N)&&(u-k[u]<1)) continue;
		if((u+k[u]>N)&&(u-k[u]>=0)&&(a[u-k[u]]==-1)) 
		{
			tmp=u-k[u];
			q.push(tmp);
			a[tmp]=a[u]+1;
		}
		if((u+k[u]<=N)&&(u-k[u]<1)&&(a[u+k[u]]==-1)) 
		{
			tmp=u+k[u];
			q.push(tmp);
			a[tmp]=a[u]+1;
		}
		if((u+k[u]<=N)&&(u-k[u]>0)&&(u-k[u]==-1)&&(u+k[u]==-1)) 
		{
			tmp=u-k[u];
			q.push(tmp);
			a[tmp]=a[u]+1;
			
			tmp=u+k[u];
			q.push(tmp);
			a[tmp]=a[u]+1;
		}
	}
	
	cout<<a[B];
	return 0;
}