#include<iostream>

#include<stdio.h>


#define FOR(i,a,b) for(int i = a; i<=b; i++)


using namespace std;

bool M[20047][20047];


int diry[] = {0,1,0,-1,1,-1,-1,1};
int dirx[] = {1,0,-1,0,-1,1,-1,1};
int Y, X, Q;


bool ok(int y, int x)
{
	return y >= 0 && y < Y && x >= 0 && x < X;
}


int main()
{
	
	scanf("%d %d %d", &X, &Y, &Q);
	
	while(X != 0 || Y != 0 || Q != 0)
	{
		FOR(i,0,Y-1)
			FOR(j,0,X-1)
				M[i][j] = true;
				
		while(Q--)
		{
			int x, y;
			scanf("%d %d", &x, &y);
			x--; y--;
			FOR(dir,0,7)FOR(k,0,max(Y,X))
			{
				int i = y + k*diry[dir];
				int j = x + k*dirx[dir];
				if (ok(i,j))
					M[i][j] = false;
			}
		}
	/*	
		FOR(i,0,Y-1)
		{
			FOR(j,0,X-1)
				printf("%c", (M[i][j])?'1':'0');
			printf("\n");
		}
	*/
		int sum = 0;
		FOR(i,0,Y-1)
			FOR(j,0,X-1)
				if (M[i][j])
					sum++;
		printf("%d\n", sum);
		
		scanf("%d %d %d", &X, &Y, &Q);
	}
	
	return 0;
}