Count Black Squares on a Chessboard

Given a chessboard with n rows and n columns, the squares are colored in an alternating pattern starting with a white square in the top-left corner. Your task is to compute the number of black squares on the board. Note that when the total number of squares, \(n^2\), is odd, the number of black squares is \(\lfloor\frac{n^2}{2}\rfloor\). When \(n^2\) is even, exactly half of the squares are black.

Input Example: For an input of 4, the chessboard is 4x4 and the number of black squares is 8.

Note: You should read the input from stdin and output the result to stdout.

inputFormat

The input consists of a single integer n (1 ≤ n ≤ 10^9), representing the size of the chessboard.

The input is provided via stdin.

outputFormat

Output a single integer, the number of black squares on the n x n chessboard.

The output should be written to stdout.

1

0