Competitions

Triangle Counting

You are given n rods of length 1, 2, . . . , n. You have to pick any 3 of them and build a triangle. How many distinct triangles can you make? Note that, two triangles will be considered different if they have at least 1 pair of arms with different length.

Input

Each line has one positive integer n (3n106). The end of input will be indicated by a case with n < 3. This case should not be processed.

Output

For each test case, print the number of distinct triangles you can make.

Time limit 1 second
Memory limit 128 MiB
Input example #1
5
8
0

Output example #1
3
22