Code copying is a major problem on many online programming judges. There are ~N~ coders, of which some of them copy code from others. Coder ~i~ knows that only coder ~a_i~ copied from them.

There are always some "sources" from which coders copy from. A "source" is defined as a coder who does not copy from anyone. Your task is to find out how many "sources" there are.

Input Specification

The first line will contain the integer ~N~ ~(1 \le N \le 10^6)~, the number of coders there are.

The second line will contain ~N~ integers, ~a_1, a_2, \dots, a_N~ ~(0 \le a_i < i)~. The ~i^{th}~ integer means that coder ~a_i~ copies from coder ~i~. If ~a_i=0~, this means no coders copies from coder ~i~.

Output Specification

Output the number of "sources".

Constraints

Subtask 1 [20%]

~N \le 1\,000~

Subtask 2 [80%]

No additional constraints.

Sample Input 1

5
0 1 1 3 2

Sample Output 1

2

Sample Input 2

9
0 1 1 3 4 5 6 4 6

Sample Output 2

4