#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
using namespace std;

#define ll long long
#define INF (1 << 30)
#define INFLL (1LL << 60)

int card_mark[1000010] = {};
bool used_mark[1000010] = {};
bool used_num[1000010] = {};
int main() {
	ll w,h,n,s,k;
	cin >> w >> h >> n;
	for(int i = 0;i < w;i++){
		card_mark[i] = h;
	}
	for(int i = 0;i < n;i++){
		cin >> s >> k;
		s--,k--;
		card_mark[s]--;
		used_mark[s] = true;
		used_num[k] = true;
	}

	ll ans = 0,ans2 = 0,memo = 0;
	for(int i = 0;i < h;i++){
		if(used_num[i]) memo++;
	}
	for(int i = 0;i < w;i++){
		if(card_mark[i] != h) ans += card_mark[i];
		if(used_mark[i]) continue;
		ans2 += memo;
	}
	cout << ans + ans2 << endl;
	return 0;
}