#include <iostream>
struct Card {
	int s, k;
};

int main() {
	int w, h, n;
	std::cin.tie(0);
	std::ios::sync_with_stdio(false);
	std::cin >> w;
	std::cin >> h;
	std::cin >> n;
	Card* card = new Card[n];
	int count = 0;
	int sf, kf, rs = 0, rk = 0;
	for (int i = 0; i < n; ++i) {
		std::cin >> card[i].s;
		std::cin >> card[i].k;
		for (sf = 0; sf < i; ++sf) {
			if (card[i].s == card[sf].s) {
				sf = -1;
				++rk;
				break;
			}
		}
		for (kf = 0; kf < i; ++kf) {
			if (card[i].k == card[kf].k) {
				kf = -1;
				++rs;
				break;
			}
		}
		if (sf < 0 && kf < 0) {
			--count;
		}
		else {
			count += (sf >= 0) ? h - 1 - sf + rs : sf;
			count += (kf >= 0) ? w - 1 - kf + rk : kf;
		}
	}
	std::cout << count << std::endl;
}