#include<iostream>
using namespace std;
int n, a, b;
int map[201];
int book[201];
int mins=99999;
void dfs(int x,int step)
{
	if (x == b)
	{
		if (mins > step)mins = step;
		return;
	}
	int xt;
	int move[2] = { map[x],-map[x] };
	for (int i = 0; i < 2; i++)
	{
		xt = x + move[i];
		if (xt <= 0 || xt > n || book[xt])
			continue;
		book[xt] = 1;
		dfs(xt, step + 1);
		book[xt] = 0;
	}
	return;
	
}
int main()
{
	cin >> n >> a >> b;
	for (int i = 1; i <= n; i++)
		cin >> map[i];
	dfs(a, 0);
	if (mins == 99999)cout << -1;
	else cout << mins;
}