## Problem B. How many iterations? ≡

• problems
 Author: I. Tuphanov Time limit: 1 sec Input file: input.txt Memory limit: 256 Mb Output file: output.txt

### Statement

Young programmer Vasya is learning the beginnings of the algorithm complexity theory. For starters, he wants to be able to quickly estimate the number of iterations of nested loops. As a first example, he wrote the following code:

 C Pascal long long f(int n) { long long ans = 0; for (int i = 1; i <= n; i++) for (int j = i+1; j <= n; j++) for (int k = j+1; k <= n; k++) ans++; return ans; }  function f(n: integer): int64; var i, j, k: integer; begin result := 0; for i := 1 to n do for j := i+1 to n do for k := j+1 to n do inc(result); end; 

Using your knowledge of the subject, help Vasya calculate f(n) for given n.

### Input file format

Input file contains an integer n.

### Output file format

Output file must contain a single integer — f(n).

1 ≤ n ≤ 106

### Sample tests

No. Input file (input.txt) Output file (output.txt)
1
1

0
2
1000
166167000


0.091s 0.012s 13