#include <iostream>
using namespace std;
int n,a,b;
int move[300];
int point;

int func(int p,int ans)
{
	//cout << p << " ";
	if(p==b) {
		cout << ans;
		point = 1;
		return 0;
	}
	int num=0;
	if(p+move[p]<=n) {
		func(p+move[p],ans+1);
	}
		
	else 
		num++;
	
	if(p-move[p]>=1)
		func(p-move[p],ans+1);
	else 
		num++;
	
	if(n==2){
		cout << -1;
		return 0;
	}
	return 0;
}

int main()
{
	cin >> n >> a >> b;
	for(int i=1;i<=n;i++)
	{
		cin >> move[i];
	}
	func(a,0);
	if(point==0)
		cout << -1;
	return 0;
}