CSES - HIIT Open 2017 - Algorithm
  • Time limit: 0.50 s
  • Memory limit: 512 MB
Uolevi has created the following algorithm:
long long z = 0;
for (int a = 1; a <= n; a++)
    for (int b = a; b <= n; b++)
        for (int c = a; c <= b; c++)
            z++;
cout << z << "\n";
Your task is to find out what the algorithm prints.

Input

The only input line contains an integer $n$: the input for the algorithm.

Output

Print the value of $z$ at the end of the algorithm.

Constraints
  • $1 \le n \le 10^6$
Example

Input:
5

Output:
35