#include<iostream>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<cstdio>
using namespace std;
int k[210];
int s[210][3];
int head,rear;
bool isUse[210];
int main(){
	int n,a,b;
	cin>>n>>a>>b;
	for(int i=1;i<=n;i++){
		cin>>k[i];
	}
	rear++;
	s[rear][0]=a;
	s[rear][1]=0;
	while(head<rear){
		head++;
		int x=s[head][0],y=s[head][1];
		if(x==b){
			cout<<y;
			return 0;
		}
		int x1=x+k[x];
		int x2=x-k[x];
		if(x1>=1&&x1<=n){
			rear++;
			s[rear][0]=x1;
			s[rear][1]=y+1;
		}
		if(x2>=1&&x2<=n){
			rear++;
			s[rear][0]=x2;
			s[rear][1]=y+1;
		}
	}
    return 0;
}