#include <iostream>
#include <map>

using namespace std;

int main(int argc, const char* argv[])
{
	int W, H;
	int N;
	cin >> W >> H >> N;
	map<int, bool> wm;
	map<int, bool> hm;
	uint64_t cnt = 0;
	int S[N];
	int K[N];
	for (int i				 = 0; i < N; i++) cin >> S[i] >> K[i];
	for (auto&& s : S) wm[s] = true;
	for (auto&& k : K) hm[k] = true;
	uint64_t hms			 = hm.size();
	uint64_t wms			 = wm.size();
	for (int i = 1; i <= W; i++)
		if (wm[i]) cnt += H - hms;
	for (int i = 1; i <= H; i++)
		if (hm[i]) cnt += W - wms;
	//	重複削除分
	cnt += hms * wms - N;
	cout << cnt << endl;
	return 0;
}