import java.util.Arrays;
import java.util.Scanner;

public class Yukicoder11 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int W = sc.nextInt();
		int H = sc.nextInt();
		int N = sc.nextInt();

		int[] mark = new int[W];
		int[] num = new int[H];
		long res = 0, count = 0;

		Arrays.fill(mark, 0);
		Arrays.fill(num, 0);

		for (int i = 0; i < N; i++) {
			mark[sc.nextInt() - 1]++;
			num[sc.nextInt() - 1]++;
		}

		for (int i = 0; i < W; i++)
			if (mark[i] > 0) {
				res += H - mark[i];
				count++;
			}

		for (int i = 0; i < H; i++)
			if (num[i] > 0){
				res += W - count;
			}
		System.out.println(res);
	}
}