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]);
            boolean[][] arr = new boolean[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] = true;
                queens.add(new Queen(k-1,m-1));
            }
            boolean[] radek = new boolean[a];
            boolean[] sloup = new boolean[b];
            boolean[] diagL = new boolean[a+b];
            boolean[] diagR = new boolean[a+b];
            int CON = 20000;
            //roviny
            for(Queen q : queens){
                radek[q.i] = true;
                sloup[q.j] = true;
                diagL[q.i+q.j] = true;
                diagR[q.j-q.i+a-1] = true;
//                
//                for(int i = 0; i < a; i++){
//                    arr[i][q.j] = true;
//                }
//                for(int i = 0; i < b; i++){
//                    arr[q.i][i] = true;
//                }
//                //diagonaly
//                for(int i =1; i< a; i++){
//                    if(q.i+i < a && q.j +i < b){
//                        arr[q.i+i][q.j+i] = true;
//                    }
//                    if(q.i-i >= 0 && q.j +i < b){
//                        arr[q.i-i][q.j+i] = true;
//                    }
//                    if(q.i+i < a && q.j -i >= 0){
//                        arr[q.i+i][q.j-i] = true;
//                    }
//                    if(q.i-i >= 0 && q.j -i >=0){
//                        arr[q.i-i][q.j-i] = true;
//                    }
//                }
            }
            int sum = 0;
            for(int i = 0; i < radek.length; i++){
                for(int j = 0; j< sloup.length; j++){
                    if(!radek[i]&& !sloup[j] && !diagL[i + j] && !diagR[i - j+a] ){
                        sum++;
                    }
                }
                
            }
            
            
            
//            int sum = 0;
//            for(int i = 0; i<arr.length; i++){
//                for(int j = 0; j < arr[i].length; j++){
//                    if(!arr[i][j]){
//                        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;
        }
        
    }

}