#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>
#include <set>

using namespace std;

int main() {
	int w, h, n;
	cin >> w >> h >> n;

	vector<int> s(n);
	vector<int> k(n);
	for (int i = 0; i < n; i++) {
		cin >> s[i] >> k[i];
	}

	set<int> used_w, used_h;

	long long total = 0;
	for (int i = 0; i < n; i++) {
		if (used_w.count(s[i]) == 0) {
			total += h - used_h.size() - 1;
		}
		if (used_h.count(k[i]) == 0) {
			total += w - used_w.size() - 1;
		}
		used_w.insert(s[i]);
		used_h.insert(k[i]);
	}

	cout << total << endl;
	return 0;
}