#include <iostream>
#include <queue>
#include <vector>
using namespace std;

int dir[2] = { -1,1 };

int least(int a, int b, vector<int> v, int n, vector<bool> visited)
{
	bool flag = 0;
	int sum = 0;
	queue<int> q;
	visited[a] = true;
	q.push(a);
	while (!q.empty())
	{
		int size = q.size();//最关键的地方
		while (size--)
		{
			int t = q.front();
			q.pop();
			for (int i = 0; i < 2; i++)
			{
				int cur = t + dir[i] * v[t];
				if (v[t] == 0)
					return -1;
				if (cur == b)
				{
					flag = 1;
					return sum + 1;
				}
				if (cur > 0 && cur <= n && !visited[cur])
				{
					visited[cur] = true;
					q.push(cur);
				}
			}
		}
		sum++;
	}
	if (flag == 0)
		return -1;
}

int main()
{
	int n, a, b;
	cin >> n >> a >> b;
	vector<int> v(n + 1);
	vector<bool>visited(n + 1, false);
	for (int i = 1; i <= n; i++)
	{
		int t;
		cin >> t;...