#include <stdio.h>

#define CHESS_BOARD_SIZE 20010

char chessboard[CHESS_BOARD_SIZE][CHESS_BOARD_SIZE];

void nullArray(int x, int y){
	int i, j;
	for (i = 1; i <= x; i++) {
		for (j = 1; j <= y; j++) {
			chessboard[i][j] = 0;
		}
	}
}

int main(int argc, char** argv) {
	int i, j, x, y, n;
	int a, b, leftx;
	int suma;
	
	scanf("%d %d %d", &x, &y, &n);
	while (x+y+n > 1) {
		suma = x*y;
		if (n > 0){
			nullArray(x, y);
		}
		while (n--) {
			scanf("%d %d", &a, &b);
			/* zakazuju cely radek */
			for (i = 1; i <= y; i++) {
				if (chessboard[a][i] == 0) {
					chessboard[a][i] = 1;
					suma--;
				}
			}
			/* zakazuju cely sloupec */
			for (i = 1; i <= x; i++) {
				if (chessboard[i][b] == 0) {
					chessboard[i][b] = 1;
					suma--;
				}
			}
			/* zakazuju celou diagonalu zleva shora */
			leftx = (a < b) ? a : b;
			for (i = a-leftx+1, j = b-leftx+1; i <= x && j <= y; i++, j++) {
				if (chessboard[i][j] == 0) {
					chessboard[i][j] = 1;
					suma--;
				}
			}
			/* zakazuju celou diagonalu zprava shora */
			leftx = (a < y-b+1) ? a : y-b+1;
			leftx--;
			for (i = a-leftx, j = b+leftx; i <= x && j > 0; i++, j--) {
				if (chessboard[i][j] == 0) {
					chessboard[i][j] = 1;
					suma--;
				}
			}
		}
		/*
		for (i = 1; i <= x; i++) {
			for (j = 1; j <= y; j++) {
				printf("%d ", chessboard[i][j]);
			}
			printf("\n");
		}
		*/
		printf("%d\n", suma);
		scanf("%d %d %d", &x, &y, &n);
	}
	
	return 0;
}