Problem Statement

Takahashi has N teeth, one in each of the holes numbered $1, 2, \dots, N$.
Dentist Aoki will perform Q treatments on these teeth and holes.
In the i-th treatment, hole T_i is treated as follows:

• If there is a tooth in hole T_i, remove the tooth from hole T_i.
• If there is no tooth in hole T_i (i.e., the hole is empty), grow a tooth in hole T_i.

After all treatments are completed, how many teeth does Takahashi have?

Input

The input is given from Standard Input in the following format:
N Q
$T_1 T_2 \dots T_Q$

Output

Print the number of teeth as an integer.

Constraints

• All input values are integers.
• $1 \le N, Q \le 1000$
• $1 \le T_i \le N$

Sample Input 1

30 6
2 9 18 27 18 9

Sample Output 1

28

Initially, Takahashi has 30 teeth, and Aoki performs six treatments.

• In the first treatment, hole 2 is treated. There is a tooth in hole 2, so it is removed.
• In the second treatment, hole 9 is treated. There is a tooth in hole 9, so it is removed.
• In the third treatment, hole 18 is treated. There is a tooth in hole 18, so it is removed.
• In the fourth treatment, hole 27 is treated. There is a tooth in hole 27, so it is removed.
• In the fifth treatment, hole 18 is treated. There is no tooth in hole 18, so a tooth is grown.
• In the sixth treatment, hole 9 is treated. There is no tooth in hole 9, so a tooth is grown.

The final count of teeth is 28.

Sample Input 2

1 7
1 1 1 1 1 1 1

Sample Output 2

0

Sample Input 3

9 20
9 5 1 2 2 2 8 9 2 1 6 2 6 5 8 7 8 5 9 8

Sample Output 3

5

见题面 Input 部分

见题面 Output 部分