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

#define max(a, b) ((a) >= (b) ? (a) : (b))
#define min(a, b) ((a) <= (b) ? (a) : (b))

int main() {
    int p_x, p_y, q_x, q_y;
    long unsigned p_queens, p_poss;
    long unsigned i, j;
    long posun;
    while (scanf("%d%d%lu\n", &p_x, &p_y, &p_queens), p_x != 0 || p_y != 0 || p_queens != 0) {
        int **pole;
        pole = (int**) malloc (p_x * sizeof(int*));
        for (i = 0; i < p_x; i++) {
            pole[i] = (int*) malloc (p_y * sizeof(int));
            for (j = 0; j < p_y; j++) pole[i][j] = 1;
        }
        for (i = 0; i < p_queens; i++) {
            scanf("%d%d\n", &q_x, &q_y);
            q_x--; q_y--;
            for (j = 0; j < p_y; j++) pole[q_x][j] = 0;
            for (j = 0; j < p_x; j++) pole[j][q_y] = 0;
            posun = q_x - q_y;
            for (j = max(0, -posun); j < min(p_y, p_x - posun); j++) pole[posun+j][j] = 0;
            posun = q_x + q_y;
            for (j = max(0, posun - p_x + 1); j < min(p_y, posun + 1); j++) pole[posun-j][j] = 0;
        }
        p_poss = 0;
        for (i = 0; i < p_x; i++)
            for (j = 0; j < p_y; j++)
                if (pole[i][j]) p_poss++;
        printf("%lu\n", p_poss);
    }
    
    
    
 return 0;   
}