Maximum Garden Area

You are given an integer P which represents the total length of the available fencing material. Your task is to compute the maximum possible area of a rectangular garden that can be enclosed using this amount of fencing. The sides of the rectangle must have integer lengths.

In mathematical terms, if the sides of the rectangle are l and w (both integers), and the perimeter satisfies \[ 2l + 2w \le P, \] find the maximum value of l \times w. If no valid rectangle can be formed, output 0.

Note: The solution should read input from standard input (stdin) and write the result to standard output (stdout).

inputFormat

The input consists of a single integer P (\(1 \le P \le 10^9\)) provided in one line representing the total length of the fencing material available.

outputFormat

Output a single integer which is the maximum possible area of a rectangular garden that can be enclosed with the given fencing, under the constraint that the side lengths are integers.

## sample

12

9

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