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.