Teemu has written the following program:

long long z = 0;
for (int a = 0; a <= n; a++)
    for (int b = n; b >= 0; b--)
        for (int c = -a; c < b; c++)
            z++;
cout << z << "\n";

Your task is to find out what the program outputs.

Input

The only input line contains integer n: the input for the program.

Output

Print the value of z at the end of the program

Limits

• 1 \le n \le 10^6

Example

Input:

4

Output:

100