H

#include<bits/stdc++.h>
using namespace std;
const int maxn=2e2+9;
int d[maxn],k[maxn];
int main(){
    int N,A,B;
    cin>>N>>A>>B;
    for(int i=1;i<=N;i++)cin>>k[i];
    memset(d,-1,sizeof(d));
    d[A]=0;
    queue<int> q;
    q.push(A);
    while(q.size()) {
        int r=q.front();
        q.pop();
        if (r+k[r]<=N&&d[r+k[r]]==-1) {
            d[r+k[r]]=d[r]+1;
            q.push(r+k[r]);
        }
        if (r-k[r] >=1&&d[r-k[r]]==-1) {
            d[r-k[r]]=d[r]+1;
            q.push(r-k[r]);
        }
    }
    cout<<d[B];
    return 0;
}