#include<iostream>
#include<queue>
#include<cstring>

using namespace std;

const int N = 210;

int a[N];
int n,start,tail,ans;

int bfs(){
	bool vis[N];
	memset(vis,false,sizeof vis);
	vis[start] = true;
	queue<int> q;
	q.push(start);
	while(q.size()){
		if(q.front() == tail) return ans;
		int t = q.front();
		q.pop();
		if(t + a[t] <= n && !vis[t + a[t]]) {
			q.push(t + a[t]);
			vis[t + a[t]] = true;
		}
		if(t - a[t] >= 1 && !vis[t - a[t]]) {
			q.push(t - a[t]);
			vis[t - a[t]] = true;
		}
		ans ++ ;
	}
	return -1;
}

int main(){
	cin >> n >> start >> tail;
	for(int i = 1;i <= n;i ++ ){
		cin >> a[i];
	}
	cout << bfs();
	return 0;
}