#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int main() {
    ll w, h, n;
    cin>>w>>h>>n;
    set<ll> suits;
    set<ll> nums;
    for (int i=0; i < n; i++) {
        ll s, k;
        cin>>s>>k;
        suits.insert(s);
        nums.insert(k);
    }
    ll ns = suits.size();
    ll nn = nums.size();
    cout << ns*nn + (w-ns)*nn + ns*(h-nn) - n << endl;
    return 0;
}