Fathers problems
In this task, Vasilyek, acting as an adult child who no longer believed that St. Nicholas carries gifts. But every year, waking up on December 19, sunet hand under the pillow. In that year he decided to ask the parents, so they gave him a brand new laptop. In response to his request, his father said: "If you decide to challenge that you are already a few days you can not overpower, you will have happiness". The task was as follows. Given a rectangle of N*M, divided by the unit square. In one operation to carry out all possible diagonals in all the squares, which were before the operation. This operation must be repeated K times. You must then count the number of triangles in the middle of which nebylo held a single segment. Remain covsem little, so Vasilyek need your help.
Input
In the first row are given two natural numbers N and M - the size of the rectangle. Second line is given an integer K - the number of applications of the operation.
Output
The answer to this Vasilyek task. It is guaranteed that the answer will not exceed 10^18.