Problem2866--Repaintings

2866: Repaintings

Time Limit: 2 Sec  Memory Limit: 256 MB
Submit: 0  Solved: 0
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Description

time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

A chessboard n×m in size is given. During the zero minute we repaint all the black squares to the 0 color. During the i-th minute we repaint to the i color the initially black squares that have exactly four corner-adjacent squares painted i-1 (all such squares are repainted simultaneously). This process continues ad infinitum. You have to figure out how many squares we repainted exactly x times.

The upper left square of the board has to be assumed to be always black. Two squares are called corner-adjacent, if they have exactly one common point.

Input

The first line contains integers n and m (1≤n,m≤5000). The second line contains integer x (1≤x≤109).

Output

Print how many squares will be painted exactly x times.

Examples
Input
3 3
1
Output
4
Input
3 3
2
Output
1
Input
1 1
1
Output
1

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