#include <bits/stdc++.h>
using namespace std;
int t[201];
bool vis[201];
int cnt,minc=0x7ffffff;
int a,b,n;
void dfs(int cur,int cnt)
{
    if (cur<1||cur>n||vis[cur])
    {
        return;
    }
    if (cur==b)
    {
        if (cnt<minc)
        {
            minc=cnt;
        }
    }
    if (cnt>minc)
    {
        return;
    }
    vis[cur]=true;
    dfs(cur+t[cur],cnt+1);
    dfs(cur-t[cur],cnt+1);
    vis[cur]=false;
}
int main()
{
    memset(vis,false,sizeof(vis));
    scanf("%d %d",&n,&a,&b);
    for (int i=1;i<=n;i++)
    {
        scanf("%d",&t[i]);
    }
    dfs(a,0);
    if (minc==0x7ffffff)
    {
        printf("-1\n");
        return 0;
    }
    printf("%d\n",minc);
    return 0;
}