import java.io.*;
import java.util.*;

public class Main {

    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int w = Integer.parseInt(br.readLine());
        int h = Integer.parseInt(br.readLine());
        int n = Integer.parseInt(br.readLine());

        TreeMap<Integer, Integer> s = new TreeMap();
        TreeMap<Integer, Integer> k = new TreeMap();

        long count = 0;
        for (int i = 0; i < n; i++) {
            long tmpCount = 0;
            String[] tmp = br.readLine().split(" ");
            int[] tmpSk = new int[]{Integer.parseInt(tmp[0]),
                Integer.parseInt(tmp[1])};

            if (!s.containsKey(tmpSk[0]) && !k.containsKey(tmpSk[1])) {
                tmpCount = w + h - 2 - s.size() - k.size();
                s.put(tmpSk[0], 0);
                k.put(tmpSk[1], 0);
            } else if (s.containsKey(tmpSk[0])) {
                tmpCount = w - 2 - (s.size() - 1);
                k.put(tmpSk[1], 0);
            } else if (k.containsKey(tmpSk[1])) {
                tmpCount = h - 2 - (k.size() - 1);
                s.put(tmpSk[0], 0);
            }

            count += tmpCount;
        }

        System.out.println(count);
    }
}