#include<bits/stdc++.h>
using namespace std;
const int N=210;
int dist[N];
int dx[N];
int dy[]={-1,1};
int n,A,B;
int bfs(int x)
{
	memset(dist,0x3f,sizeof dist);
	dist[x]=0;
	queue<int> q;
	q.push(x);
	while(q.size())
	{
		int t=q.front();
		q.pop();
		if(t==B)
		{
			return dist[B];
		}
		for(int i=0;i<2;i++)
		{
			int a=t+dx[t]*dy[i];
			if(a<0||a>n)
			{
				continue;
			}
			if(dist[a]!=0x3f3f3f3f)
			{
				continue;
			}
			dist[a]=dist[t]+1;
			q.push(a);
		}
	}
	return -1;
}
int main()
{
	cin>>n>>A>>B;
	for(int i=1;i<=n;i++)
	{
		cin>>dx[i];
	}
	cout<<bfs(A);
	return 0;
}