/*奇怪的电梯*/

#include <bits/stdc++.h>
using namespace std;
struct state
{
    int y;
    int step;
};
int k[1008];
state f,t;
bool ceng[10008];
int n,a,b;
int BFS(state s)
{
    queue<state>q;
    q.push(s);
    ceng[s.y]=1;
    while(!q.empty())
    {
        t=q.front();
        if(t.y==b)
        {
            return f.step;
        }
        t.step++;
        if(t.y<b)
        {
            f=t;
            f.y+=k[f.y];
            if(ceng[f.y]==0)
            {
                q.push(f);
                ceng[f.y]=1;
            }
        }
        if(t.y-k[t.y]>=1)
        {
            f=t;
            f.y-=k[f.y];
            if(ceng[f.y]==0)
            {
                q.push(f);
                ceng[f.y]=1;
            }
        }
        q.pop();
    }
    return -1;
}
int main()
{
    
    cin>>n>>a>>b;
    for(int i=1;i<=n;i++)
        cin>>k[i];
    state x;
    x.y=a;
    x.step=0;
    cout<<BFS(x);
}