#include <stdio.h>

int matica[20001][20001];
int kralovna_x, kralovna_y;
int velkost_x, velkost_y;


int SpocitajVolne() {
	int i = 0;
	int j = 0;
	int spolu = 0;	
	for(i=0; i<=velkost_x;i++) {
		for(j=0; j<=velkost_y; j++){
			if(matica[i][j]==0) {
				spolu++;			
			}			
		}
	}
	return spolu;
}


void vymazPoziciu(int x, int y) {
	matica[x][y] = 1;
	int max = velkost_y;
	if(velkost_x > velkost_y) {
		max = velkost_x;	
	}

	int i=0;
	for(i=0; i<=velkost_y;i++) {
		matica[x][i] = 1;		
	}
	for(i=0; i<=velkost_x;i++) {
		matica[i][y] = 1;		
	}
	int x1,y1;
	
	for(i=0; i<=max;i++) {
		x1 = x-i;
		y1 = y-i;		
		if((x1>=0)&&(y1>=0)) {
			matica[x1][y1] = 1;
		}

		x1 = x+i;
		y1 = y-i;		
		if((x1<=velkost_x)&&(y1>=0)) {
			matica[x1][y1] = 1;
		}

		x1 = x+i;
		y1 = y+i;		
		if((x1<=velkost_x)&&(y1<=velkost_y)) {
			matica[x1][y1] = 1;
		}
		x1 = x-i;
		y1 = y+i;		
		if((x1>=0)&&(y1<=velkost_y)) {
			matica[x1][y1] = 1;
		}
	}
}

int NacitajPlochu() {
	int i=0;
	int j=0;
	int x,y,n;
	scanf("%d %d %d",&x, &y, &n);
	if(((y > 20000) || (x > 20000)) || ((y==0) && (x==0) && (n==0))) {
		return 1;
	}	
	/* *matica =(int**)malloc(sizeof(int)* x);
         for(i=0;i<x;i++)
           matica[i] = (int*)malloc(sizeof(int)* y);*/	
	velkost_x = x-1;
	velkost_y = y-1;
	for(i=0; i<x; i++) {
		for(j=0; j<y; j++) {
			matica[i][j] = 0;
		}
	}
	
	i=0;
	for(i=0; i<n; i++) {
		scanf("%d %d",&kralovna_x, &kralovna_y);	
		vymazPoziciu(kralovna_x-1, kralovna_y-1);
	}

	return 0;
}



int main() {
	while(NacitajPlochu()==0) {
		printf("%d\n",SpocitajVolne());	
	}
	
	return 0;
}