#include<bits/stdc++.h>
using namespace std;
const int N=210;
int dist[N];
int dx[N];
int dy[]={-1,1};
int n,A,B;
int bfs(int x)
{
   memset(dist,0x3f,sizeof dist);
   dist[x]=0;
   queue<int> q;
   q.push(x);
   while(q.size())
   {
      int t=q.front();
      q.pop();
      if(t==B)
      {
         return dist[B];
      }
      for(int i=0;i<2;i++)
      {
         int a=t+dx[t]*dy[i];
         if(a<0||a>n)
         {
            continue;
         }
         if(dist[a]!=0x3f3f3f3f)
         {
            continue;
         }
         dist[a]=dist[t]+1;
         q.push(a);
      }
   }
   return -1;
}
int main()
{
   cin>>n>>A>>B;
   for(int i=1;i<=n;i++)
   {
      cin>>dx[i];
   }
   cout<<bfs(A);
   return 0;
}