#include <bits/stdc++.h>
#define endl '\n'
using namespace std;

int n, a, b;
int cnt = 0;
int arr[100100];

int fx[] = {0, 1, -1};

int q[100000][2]; // 下标0表示次数 

void bfs(int k){
	int head = 1, tail = 1;
	q[head][0] = 0; 
	q[head][1] = k;
	
	while(head <= tail){
		int curr = q[head][1]; //当前楼层 
		
		int tx;
		for(int i = 1; i <= 2; i++){
			tx = curr + fx[i] * arr[curr];
			
			if(tx >= 1 && tx <= n){
				tail++;
				q[tail][0] = q[head][0] + 1;
				q[tail][1] = tx;
				
				if(tx == b) {
					cout << q[tail][0];
					exit(0); 
				}
			}
		}
		head++;
	}
}

int main(){
	cin >> n >> a >> b;
	if(a == b){
		cout << 0;
		return 0;
	}
	for(int i = 1; i <= n; i++){
		cin >> arr[i];
	}
	
	bfs(a);
	
	cout << -1;
	return 0;
}