import java.util.Scanner;
import java.util.TreeSet;
public class Cardmatch {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int W = s.nextInt(),H = s.nextInt(),N = s.nextInt();
		int[] S = new int[N];
		int[] K = new int[N];
		TreeSet<Integer> Mark = new TreeSet<>();
		TreeSet<Integer> Number = new TreeSet<>();
		for(int i = 0;i < N ;i++){
			S[i] = s.nextInt();
			K[i] = s.nextInt();
		}
		s.close();
		long count = 0;
		for(int i = 0;i < N;i++){
			if(Mark.contains(S[i]) && Number.contains(K[i])){
				count--;
			}else if(Mark.contains(S[i])){
				count += (W - Mark.size()-1);
				Number.add(K[i]);
			}else if(Number.contains(K[i])){
				count += (H - Number.size()-1);
				Mark.add(S[i]);
			}else{
				count += (W-Mark.size() + H-Number.size() -2);
				Mark.add(S[i]);
				Number.add(K[i]);
			}
		}
		System.out.println(count);
		

	}

}