[ABC263B] Ancestor

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.

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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.

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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 $2$.

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Sample Input 2

10
1 2 3 4 5 6 7 8 9

Sample Output 2

9

从节点 $n$ 暴力往上跳就可以了。

#include<cstdio>
const int N=55;
int p[N],n,cnt;
int main()
{
	scanf("%d",&n);
	for(int i=2;i<=n;i++)
		scanf("%d",p+i);
	while(n!=1)
		++cnt,n=p[n];
	printf("%d",cnt);
}