题目描述
You are given an $H \times W$ grid. The square at the top-left corner will be represented by (0, 0), and the square at the bottom-right corner will be represented by (H-1, W-1).
Of those squares, N squares (x_1, y_1), (x_2, y_2), ..., (x_N, y_N) are painted black, and the other squares are painted white.
Let the shortest distance between white squares A and B be the minimum number of moves required to reach B from A visiting only white squares, where one can travel to an adjacent square sharing a side (up, down, left or right) in one move.
Since there are H × W - N white squares in total, there are _{(H×W-N)}C_2 ways to choose two of the white squares.
For each of these _{(H×W-N)}C_2 ways, find the shortest distance between the chosen squares, then find the sum of all those distances, modulo 1 000 000 007=10^9+7.
Constraints
- $1 \leq H, W \leq 10^6$
- $1 \leq N \leq 30$
- $0 \leq x_i \leq H-1$
- $0 \leq y_i \leq W-1$
- If $i \neq j$, then either $x_i \neq x_j$ or $y_i \neq y_j$.
- There is at least one white square.
- For every pair of white squares A and B, it is possible to reach B from A visiting only white squares.
Input
Input is given from Standard Input in the following format:
H W
N
x_1 y_1
x_2 y_2
:
x_N y_N
Output
Print the sum of the shortest distances, modulo 10^9+7.
Examples
Input
2 3
1
1 1
Output
20
Input
2 3
1
1 2
Output
16
Input
3 3
1
1 1
Output
64
Input
4 4
4
0 1
1 1
2 1
2 2
Output
268
Input
1000000 1000000
1
0 0
Output
333211937
输入格式
见题面
输出格式
见题面