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


/*int x, y, max;
int * pole;*/


/*int map(int posX, int posY) {
	printf("%d %d %d", posX, posY, (posX + x * posY));
	return (posX + (x * posY));
}


void readQueen(int posX, int posY) {
	int i;
	posX -=1; posY -=1;
//	printf("\n\n%d %d\n\n", posX, posY);	
	for ( i = 0; i < x; ++i ){
		pole[map(i,posY)] = 0;
	}
	for ( i = 0; i < y; ++i ){
		pole[map(posX,i)] = 0;
	}
	for ( i = map(i,posY); i < max; i+= x + 1  ){		
		pole[i] = 0;
	}
	for ( i = map(i,posY); i >= 0; i-= x - 1  ){		
		pole[i] = 0;
	}
	for ( i = map(i,posY); i < max; i+= x - 1  ){		
		pole[i] = 0;
	}
	for ( i = map(i,posY); i >= 0; i-=  y + 1  ){		
		pole[i] = 0;
	}


}


int main() {
	int pocet, i, posX, posY;

	scanf("%d %d %d", &x, &y, &pocet);

	while ( x || y || pocet )
	{
		max = 	x * y;
		int * pole = (int*)malloc(sizeof(int)*(max));
		for (i = 0; i < max; ++i) pole[i] = 1;

		for (i = 0; i < pocet; ++i)
		{
			scanf("%d %d", &posX, &posY);
			readQueen(posX, posY);
		}
		int suma = 0;
		for (i = 0; i < max; ++i)
		{
			suma+=pole[i];
		}
		printf("%d\n", suma);
		free (pole);
		scanf("%d %d %d", &x, &y, &pocet);
	}
	return 0;
}*/

int mapPos(int x, int y, int delka, int sirka)
{
	return (y*delka+x);
}


int main()
{
	int delka, sirka, pocet, i, j, posX, posY;
	scanf("%d %d %d", &delka, &sirka, &pocet);
	while ( delka || sirka || pocet )
	{		
		int * pole = (int*)malloc(sizeof(int)*(delka*sirka));
		
		for (i = 0; i < (delka*sirka); ++i) pole[i] = 1;
		for (i = 0; i < pocet; ++i)
		{
			scanf("%d %d", &posX, &posY);
			posX-=1; posY-=1;
			for (j = posX; j < (delka*sirka); j+=delka) pole[j] = 0;
			for (j = mapPos(0, posY, delka, sirka); j < mapPos(delka, posY, delka, sirka); ++j) pole[j] = 0;
			for (j = mapPos(posX, posY, delka, sirka); j < (delka*sirka); j+=(delka+1)) if ((j/delka)>posX) pole[j] = 0;
			for (j = mapPos(posX, posY, delka, sirka); j < (delka*sirka); j+=(delka-1)) if ((j/delka)>posX) pole[j] = 0;
			for (j = mapPos(posX, posY, delka, sirka); j >= 0; j -= (delka-1) ) if ((j/delka)<posX) pole[j] = 0;
			for (j = mapPos(posX, posY, delka, sirka); j >= 0; j -= (delka+1) ) if ((j/delka)<posX) pole[j] = 0;
		}
		int suma = 0;
		for (i = 0; i < (delka*sirka); ++i)
		{
			if (pole[i] == 1) ++suma;
		}
		printf("%d\n", suma);
		free (pole);
		scanf("%d %d %d", &delka, &sirka, &pocet);
	}
	return 0;
}