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

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

/**
 *
 * @author cteam29
 */
public class ith {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String line;
        while(!( line = reader.readLine()).equals("0 0 0")){
            String[] l= line.split(" ");
            int a = Integer.valueOf(l[0]);
            int b = Integer.valueOf(l[1]);
            int[][] arr = new int[a][b];
            int number = Integer.valueOf(l[2]);
            for(int i=0; i<number; i++){
                line = reader.readLine();
                l = line.split(" ");
                int k = Integer.valueOf(l[0]);
                int m = Integer.valueOf(l[1]);
                arr[k-1][m-1] = -1;
                queens.add(new Queen(k-1,m-1));
            }
            //roviny
            for(Queen q : queens){
                for(int i = 0; i < a; i++){
                    arr[i][q.j] = 1;
                }
                for(int i = 0; i < b; i++){
                    arr[q.i][i] = 1;
                }
                //diagonaly
                for(int i =1; i< a; i++){
                    if(q.i+i < a && q.j +i < b){
                        arr[q.i+i][q.j+i] = 1;
                    }
                    if(q.i-i >= 0 && q.j +i < b){
                        arr[q.i-i][q.j+i] = 1;
                    }
                    if(q.i+i < a && q.j -i >= 0){
                        arr[q.i+i][q.j-i] = 1;
                    }
                    if(q.i-i >= 0 && q.j -i >=0){
                        arr[q.i-i][q.j-i] = 1;
                    }
                }
            }
            
            
            int sum = 0;
            for(int i = 0; i<arr.length; i++){
                for(int j = 0; j < arr[i].length; j++){
                    if(arr[i][j] == 0){
                        sum++;
                    }
                }
            }
            System.out.println(sum);
            
            
            queens.clear();
            
        }
    }
    
    public static ArrayList<Queen> queens = new ArrayList<Queen>();
    public static class Queen{
        public int i;
        public int j;

        public Queen(int i, int j) {
            this.i = i;
            this.j = j;
        }
        
    }

}