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CSES - HIIT Open 2017

HIIT Open 2017

Contest start:2017-05-27 11:00:00
Contest end:2017-05-27 16:00:00

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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
Example

Input:
5

Output:
35