#include<algorithm>
#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<queue>
#include<vector>
#include<stack>
#include<ctime>
#include<cstdlib>
//#include<cmath>
using namespace std;
int n,a,b,s[205],tmp[205];
int bfs(int z,int num){
	queue <pair<int,int> > q;
	q.push({a,0});
	while(!q.empty()){
		pair <int,int> N=q.front();
		q.pop();
		if(N.first==b){
			return N.second;
		}
		q.push({N.first+s[N.first],N.second+1});
		q.push({N.first-s[N.first],N.second+1});
	}
	return -1;
}
int main(){
//	freopen("GRQ.in","r",stdin);
//	freoprn("GRQ.out","w",stdout);
	scanf("%d%d%d",&n,&a,&b);
	if(a==b){
		printf("0");
		return 0;
	}
	for(int i=1;i<=n;i++){
		scanf("%d",&s[i]);
	} 
	
	printf("%d",bfs(a,0));
	return 0;
}