import java.io.BufferedReader;
import java.io.IOException;

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
import java.io.Reader;
import java.util.Scanner;

/**
 *
 * @author cteam20
 */
public class ith {
public static boolean next = true;

static Scanner sc = new Scanner(System.in);

static int pocetDam = 0;
static int X;
static int Y;

    
static String cti(){
    byte[] pole = new byte[50];
    String nacteno;
    int i;
    
    try {
    System.in.read(pole);
    nacteno = new String(pole).trim();
    
    return nacteno;
    } catch (IOException ex){
        return "0 0 0";
    }
}
      
   
    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args)  {
        try {
        String[] line = cti().split(" ");
        
        
       
         X = Integer.valueOf(line[0]); 
         Y = Integer.valueOf(line[1]); 
         pocetDam = Integer.valueOf(line[2]);
         
         do {
             
             boolean[][] souradnice = new boolean[X+1][Y+1];
             
             int x = 0,y = 0;
             
             for (int i = 0;i <pocetDam ; i++){
                 
                 line = cti().split(" ");
                 
                 
                 x = Integer.valueOf(line[0]); 
                 y = Integer.valueOf(line[1]); 
                 
                 souradnice[x][y] = true;
                 souradnice[x][0] = true;
                 souradnice[0][y] = true;
             }
                
             
             int pocetReseni =0;
             
             for (int k = 1;k < Y+1;k++){
                 
                 if (souradnice[0][k]){
                     continue;
                 }
                 
                 for (int l = 1;l<X+1;l++){
                    if (souradnice[l][0]){
                     continue;
                    }
                    
                    boolean konec = false;
                    x = l;
                    y = k;
                    
                   
                    
                    while ((x>1) && (y>1) && (!konec)) {
                        x--;
                        y--;
                        
                        if (souradnice[x][y]){
                            
                            konec = true;
                        }
                    }
                    
                    x = l;
                    y = k;
                    while (y>1 && !konec && x< X ){
                        x++;
                        y--;
                        
                        if (souradnice[x][y]){
                            
                            konec = true;
                        }
                    }
                    
                    x = l;
                    y = k;
                    while (x>1 && !konec  && y < Y){
                        x--;
                        y++;
                        if (souradnice[x][y]){
                            
                            konec = true;
                        }
                    }
                    
                    x = l;
                    y = k;
                    while ( !konec && x< X && y < Y){
                        x++;
                        y++;
                        if (souradnice[x][y]){
                            
                            konec = true;
                        }
                    }
                    
                    if (!konec){
                        pocetReseni++;
                        
                    }else {
                        
                    }
                    
                 }
             }
             
             System.out.println(""+pocetReseni);
             
             
             
             
             line = cti().split(" ");
        
        
       
         X = Integer.valueOf(line[0]); 
         Y = Integer.valueOf(line[1]); 
         pocetDam = Integer.valueOf(line[2]); 
         
         if (X == 0 && Y ==0 && pocetDam == 0){
             next=false;
         }
         
         } while (next);
        }catch (Exception ex){
            ;
        }
    }
        
}