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#### Description

The Problem:

Given the width and height of a rectangular wall and the window-border gap (minimum distance required between the perimeter of the wall and the perimeter of the window), determine the area of the largest rectangular window that can be installed on the wall.

#### Input

The input contains one line with three space-separated positive integers, w, h, and d (w, h < 1000, d < 100), representing, respectively, the wall’s width, wall’s height, and the minimum windowborder gap amount needed.

#### Output

The output should be an integer on one line by itself, which represents the area of the largest rectangular window that can be installed. If it is not possible to install a window, output 0 (zero).

#### Samples

Input Copy
40 25 5
Output
450

#### Source

UCF2018
##### Problem Information

 Time Limit: 1000MS (C/C++,Others×2) Memory Limit: 128MB (C/C++,Others×2) Special Judge: No AC/Submit: 1 / 1 Tags:
##### Contests involved

 1036. UCF 2018