#include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>
#include<limits>

#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()

using namespace std;
typedef long long ll;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ll, string> pls;

int row[1000010];
int col[1000010];

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

	ll ans = 0, dif = 0;
	for (int i = 0; i < n; i++) {
		int s, k;
		cin >> s >> k;
		if (!row[s]) {
			ans += h - 1;
			if(!col[k])
				ans -= dif;
			row[s] = 1;
		}
		else {
			ans--;
		}
		if (!col[k]) {
			ans += w - 1;
			ans -= dif;
			dif++;
			col[k] = 1;
		}
		else {
			ans--;
		}
	}
	cout << ans << endl;
	return 0;
}