#include<bits/stdc++.h>
using namespace std;
int a,b,n,k[201];
int minRes =2147483647;
void dfs(int x,int ans){
	if(x==b){
		minRes=min(minRes,ans);
		return;
	}
	if(x-k[x]<=0&&x+k[x]>n){;
		return;
	}
	if(x-k[x]<=0&&x+k[x]<=n){
		dfs(x+k[x],ans+1);
		return;//只能网上
	}
	if(x-k[x]>=1&&x+k[x]>n){
		dfs(x-k[x],ans+1);
		return;//只能往下
	}
	dfs(x+k[x],ans+1);
	dfs(x-k[x],ans+1);
}
int main(){
	cin>>n>>a>>b;
	for(int i=1;i<=n;i++){
		cin>>k[i];
	}
	dfs(a,0);
	if(minRes==2147483647)cout<<-1<<endl;
	else cout<<minRes;
	return 0;
}