#include<bits/stdc++.h>
using namespace std;
int n,a,b;
int k[201];
int sum[201];//步数 
void dfs(int f,int step){
//	cout<<f<<endl;
	if(f==b) sum[b]=min(sum[b],step-1);
	else {
		int tf=f+k[f];//向上 
		if(tf>1&&tf<=n&&sum[tf]>step+1){//在舞台上，并且步数更少
			sum[tf]=step+1;
			dfs(tf,step+1);
		} 
		tf=f-k[f];//向下 
		if(tf>1&&tf<=n&&sum[tf]>step+1) { 
			sum[tf]=step+1;
			dfs(tf,step+1);
		}
	}
}
int main(){
	cin>>n>>a>>b;
	for(int i=1;i<=n;i++) {
		cin>>k[i];
		sum[i]=10086;//最值 
	}
	dfs(a,1);
	if(sum[b]==10086) sum[b]=-1; 
	cout<<sum[b];
	return 0;
}

/**************************************************************
	Problem: 1819
	User: liuchengxuan
	Language: C++
	Result: Accepted
	Time:21 ms
	Memory:2076 kb
****************************************************************/