**Time limit:**1.00 s**Memory limit:**512 MB

Your task is to calculate the number of ways an integer n can be represented as a sum of three *distinct* positive integers.

For example, if n=9, there are 3 solutions:

- 1+2+6=9
- 1+3+5=9
- 2+3+4=9

# Input

The only input line has an integer n.

# Output

Print one line: the number of solutions.

# Example

Input:

9

Output:

3

# Grading

In each test 1 \le n \le 1000. You will get 100 points for the task if your program gives the correct answer in each test.