Author:  I. Tuphanov  Time limit:  1 sec  
Input file:  input.txt  Memory limit:  256 Mb  
Output file:  output.txt 
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 contains an integer n.
Output file must contain a single integer — f(n)
.
1 ≤ n ≤ 10^{6}
No.  Input file (input.txt ) 
Output file (output.txt ) 

1 


2 

