#include <iostream>
#include <vector>
using namespace std;
int main() {
	long long W, H, Ans = 0;
	long long Use = 0,True_num = 0;
	int N;
	cin >> W >> H >> N;
	vector<int> S(N), K(N);
	vector<int> use_mark(W,0);
	vector<bool> use_num(H, false);


	for (int i = 0; i < N;i++) {
		cin >> S[i] >> K[i];
		if (use_mark[S[i] - 1] == 0) { Use++; }
		use_mark[S[i] - 1]++;
		if (use_num[K[i] - 1] == false) {
			use_num[K[i] - 1] = true;
			True_num++;
		}
	}
	for (int i = 0; i < W;i++) {
		if (use_mark[i] != 0) {
			Ans += (H - use_mark[i]);
		}
	}
	Ans += (W - Use) * True_num;
	cout << Ans << endl;
	return 0;
}