Score : $200$ points

问题描述

设有 $N$ 个人，分别称为 Person 1、Person 2、$\ldots$、Person $N$。

其中，Person $i$ $(2 \le i \le N)$ 的父母是 Person $P_i$。这里保证 $P_i < i$。

请问 Person 1 距离 Person $N$ 有多少代？

以上为通义千问 qwen-max 翻译，仅供参考。

Problem Statement

There are $N$ people, called Person $1$, Person $2$, $\ldots$, Person $N$.

The parent of Person $i$ $(2 \le i \le N)$ is Person $P_i$. Here, it is guaranteed that $P_i < i$.

How many generations away from Person $N$ is Person $1$?

Constraints

• $2 \le N \le 50$
• $1 \le P_i < i(2 \le i \le N)$
• All values in input are integers.

Input

Input is given from Standard Input in the following format:

$N$

$P_2$ $P_3$ $\dots$ $P_N$

Output

Print the answer as a positive integer.

Sample Input 1

3
1 2

Sample Output 1

2

Person $2$ is a parent of Person $3$, and thus is one generation away from Person $3$.

Person $1$ is a parent of Person $2$, and thus is two generations away from Person $3$.

Therefore, the answer is $2$.

Sample Input 2

10
1 2 3 4 5 6 7 8 9

Sample Output 2

9

update @ 2024/3/10 11:07:20