Problem Statement

"It is not that Santa comes to good children; rather, the children Santa comes to are the good children."
In Yuki City, a town where cause and effect have been reversed, you are known as the $(P,Q)$ -Santa, the one and only Santa, reigning at the center of the city.

Yuki City is represented by the $(X,Y)$ plane, and you are at the origin $(0,0)$.
The children of the city live on lattice points of Yuki City (coordinates where $X$,$Y$ are both integers).
Your job is to deliver presents at Christmas, but your means of transportation is a sleigh pulled by special reindeer, which has excellent mobility but is restricted in the directions it can move.
As the name $(P,Q)$-Santa suggests, from the current position $(x,y)$ you can move in one move to $(x \pm P,y \pm Q)$ or $(x \pm Q,y \pm P)$.

For example, when $(P,Q)=(1,2)$, if the current position is $s$, you can move to $t$.

.t.t.
t...t
..s..
t...t
.t.t.

Input

$P$ $Q$
$N$
$X_0$ $Y_0$
$X_1$ $Y_1$
$\vdots$
$X_{N-1}$ $Y_{N-1}$

All input values are integers.
$0\le P \le 10^9$
$0\le Q \le 10^9$
$1\le N \le 10^5$
$-10^9 \le X_i \le 10^9$ , $0 \le i < N$
$-10^9 \le Y_i \le 10^9$ , $0 \le i < N$

Output

Output the number of good children on one line. Print a newline at the end.

Sample

2 3
3
2 3
3 -2
-5 -5

3

1 0
3
0 3
4 1
2 2

3

1 2
5
2 6
6 3
2 4
0 0
6 1

5

4 12
6
1 4
2 7
4 3
8 4
5 5
6 12

0