#include<bits/stdc++.h>
using namespace std;

int n,s,t,a[201],cmp[201],val[201];
int main(){
    cin>>n>>s>>t;
    int i;
    for(i=1; i<=n; i++){
        cin>>a[i];
        cmp[i]=0;
        val[i]=-1;
    }
    if(s==t){
     cout<<0;
     return 0;
    }
    int l,r,v,qu[1001];
    l=r=1;
    qu[1]=s;
    val[s]=0;
    cmp[s]=1;
    while(l<=r && r<=1000){
        v=qu[l++];
        if(v+a[v]<=n){ 
            if(cmp[v+a[v]]==0){
                qu[++r]=v+a[v];
                val[v+a[v]]=val[v]+1;
                cmp[v+a[v]]=1;
            }
        } 
        if(v-a[v]>=1){ 
            if(cmp[v-a[v]]==0){
                qu[++r]=v-a[v];
                val[v-a[v]]=val[v]+1;
                cmp[v-a[v]]=1;
            }
        } 
    }
    cout<<val[t];
    return 0;
}