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

#define NUM_CCIES	200

using namespace std;

struct Queen
{
	int x,y;
};

#define NUM_Q	20000

Queen queens[NUM_Q];

int main()
{
	bool notfirst=false;

	for(;;)
	{
		int xsize=0, ysize, numQueens;
		int xs[NUM_Q];
		int ys[NUM_Q];
		memset(xs,0,sizeof(xs));
		memset(ys,0,sizeof(ys));

		scanf("%d %d %d", &xsize, &ysize, &numQueens);

		if ( xsize==0)
			break;

		for ( int i=0; i<numQueens; ++i)
		{
			scanf("%d %d", &queens[i].x, &queens[i].y);

			xs[--queens[i].x]=1;
			ys[--queens[i].y]=1;
		}

		if ( notfirst)
			printf("\n");
		notfirst=true;

		if ( numQueens>xsize && numQueens > ysize)
		{
			printf("0");
			continue;
		}
		if ( numQueens==0)
		{
			printf("%d", xsize * ysize);
			continue;
		}

		int xcand[NUM_Q];
		int xcount=0;
		int ycand[NUM_Q];
		int ycount=0;

		for ( int i=0; i<xsize; ++i)
			if (xs[i]==0)
				xcand[xcount++]=i;
		for ( int i=0; i<ysize; ++i)
			if (ys[i]==0)
				ycand[ycount++]=i;

		int ret=0;

		for ( int i=0; i<xcount; ++i)
			for ( int j=0; j<ycount; ++j)
				for ( int k=0; k<numQueens; ++k)
				{
					if ( abs(xcand[i]-queens[k].x)==abs(ycand[j]-queens[k].y))
						break;

					if ( k==numQueens-1)
						++ret;
				}

		printf("%d", ret);
	}

	return 0;
}