#include<iostream>
#include<cstdlib>
using namespace std;
bool cs=0;
int N,A,B,a[201][2];
int book[201];
int total=999999999;
void gala(int l,int step)
{
	if(l==B)
	{
		cs=1;
		if(step<=total)
		{
			total=step;
		}
		return;
	}
	int nl;
	for(int i=0;i<=1;i++)
	{
		nl=l+a[l][i];
		if(nl>N||nl<1)
		continue;
		if(book[nl]==0)
		{
			book[nl]=1;
			gala(nl,step+1);
			book[nl]=0;
		}
	}
	return;
}
int main()
{
	cin>>N>>A>>B;
	for(int i=1;i<=N;i++)
	{
		int k;
		cin>>k;
		a[i][0]=k;
		a[i][1]=-k;
	}
	book[A]=1;
	gala(A,0);
	cout<<total;
	if(cs==0)
	cout<<-1;
	return 0;
}```