A. Golden Platetime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputYou have a plate and you want to add some gilding to it. The plate is a rectangle that we split into w\times h cells. There should be k gilded rings, the first one should go along the edge of the plate, the second one — 2 cells away from the edge and so on. Each ring has a width of 1 cell. Formally, the i-th of these rings should consist of all bordering cells on the inner rectangle of size (w - 4(i - 1))\times(h - 4(i - 1)).  The picture corresponds to the third example. Your task is to compute the number of cells to be gilded.InputThe only line contains three integers w, h and k (3 \le w, h \le 100, 1 \le k \le \left\lfloor \frac{min(n, m) + 1}{4}\right\rfloor, where \lfloor x \rfloor denotes the number x rounded down) — the number of rows, columns and the number of rings, respectively.OutputPrint a single positive integer — the number of cells to be gilded.ExamplesInput3 3 1Output8Input7 9 1Output28Input7 9 2Output40NoteThe first example is shown on the picture below.  The second example is shown on the picture below.  The third example is shown in the problem description.
Input3 3 1
Output8
['implementation', 'math', '*800']