# Byte and Chess

Execution time limit is 1 second

Runtime memory usage limit is 64 megabytes

While rushing to class, Baytik noticed a chessboard in the game room. He began to wonder how many different squares of side length k (1 ≤ k ≤ n) can fit on a chessboard of size n.

## Input

A natural number n (n ≤ 10000), representing the size of the chessboard.

## Output

A single number indicating the total number of different squares that can be placed on the chessboard.

## Examples

Input #1

Answer #1

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