#include<stdio.h>
int k[201];                          
int min=1000;
int book[201];
void dfs(int A,int B,int cnt,int N){
	if(A==B){
		if(cnt<min){
			min=cnt;
		}else if(cnt<min){
			book[A]=1;
			if(A+k[A]<=N&&book[A+k[A]]==0){
				dfs(A+k[A],B,cnt+1,N);
			}
			if(A-k[A]>0&&book[A-k[A]]==0){
				dfs(A-k[A],B,cnt+1,N);
			}
			book[A]=0;
		}
	}
}
int main(void)
{
	int N,A,B;
	scanf("%d %d %d",N,A,B);
	printf("继续\n"); 
	int a,cnt=0;
	for(a=1;a<N+1;a++){
		scanf("%d",&k[a]);
	}
	for(a=1;a<N+1;A++){
		book[a]=0;
	}
	dfs(A,B,0,N);
    if(min==1000){
    	min=-1;
	}
	printf("%d",min);
	return 0;
}