#include <stdio.h>
#include <stdlib.h>

	
bool matrix[20005][20005];

int size_x, size_y;
int count;

/*void blee(){

	for(int i =0;i<size_x;i++)
	{
		for(int j =0;j<size_y;j++)
			printf("%d ", matrix[i][j]);
		printf("\n");
	}
	printf("-------------------\n");
}*/

void clear() {
	for(int i =0;i<size_x;i++)
	{
		for(int j =0;j<size_y;j++)
			matrix[i][j] = true;
	}
}

int main(int ac, char **av) {
	
	scanf("%d %d %d", &size_x, &size_y, &count);
	while(size_x && size_y){
		clear();
		for(int  i = 0; i < count; i++) {
			int x, y;		
			scanf("%d %d\n", &x, &y);
			x--;
			y--;
			for(int j = 0; j < size_x; j++)
				matrix[j][y] = false;	
			for(int j = 0; j < size_y; j++)
				matrix[x][j] = false;
			for(int jx = x, jy = y; jx >= 0 && jy >= 0; jx--, jy--)
				matrix[jx][jy] = false;	
			for(int jx = x, jy = y; jx < size_x && jy < size_y; jx++, jy++)
				matrix[jx][jy] = false;	
			for(int jx = x, jy = y; jx >= 0 && jy < size_y; jx--, jy++)
				matrix[jx][jy] = false;			
			for(int jx = x, jy = y; jy >= 0 && jx < size_x; jx++, jy--)
				matrix[jx][jy] = false;
		}
		//blee();
		int res_count = 0;
			for(int j = 0; j < size_x; j++)
				for(int k = 0; k < size_y; k++)	
					if(matrix[j][k]) 
						res_count++;
			printf("%d\n", res_count);
		scanf("%d %d %d", &size_x, &size_y, &count);
	}	
	return 0;
}