Problem Statement

Takahashi has N friends. They have nicknames: Friend $1, Friend 2, \ldots, Friend N$.
One day, Takahashi accidentally let one of his friends, Friend X, learn his shameful secret.
For each $i = 1, 2, \ldots, N$, when Friend i learns the secret, he/she will share it with Friend A_i, if Friend A_i has not already learned it.
How many of Takahashi's friends will learn the secret in the end?

Input

Input is given from Standard Input in the following format:
N X
$A_1 A_2 \cdots A_N$

Output

Print the answer.

Constraints

• $2 \leq N \leq 10^5$
• $1 \leq X \leq N$
• $1 \leq A_i \leq N$
• $A_i \neq i$
• All values in input are integers.

Sample Input 1

4 2
3 1 1 2

Sample Output 1

3

Takahashi's secret will be learned by Friend 1, Friend 2, and Friend 3, as follows.

• One day, Takahashi let Friend 2 learn the secret.
• Friend 2 shares it with Friend 1.
• Friend 1 shares it with Friend 3.

In the end, three of his friends learn the secret, so we print 3.

Sample Input 2

20 12
7 11 10 1 7 20 14 2 17 3 2 5 19 20 8 14 18 2 10 10

Sample Output 2

7

见题面 Input 部分

见题面 Output 部分