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.

The input for each case will have only a single positive integer n(1<=n<=1000000). The end of input will be indicated by a case with n<1. This case should not be processed.

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

5
8
0

3
22