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

using ll = long long;

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  
  ll w, h, n;
  cin >> w >> h >> n;
  
  vector<ll> s(n), k(n);
  map<ll, ll> mp1, mp2;
  for (int i = 0; i < n; i++) {
    cin >> s.at(i) >> k.at(i);
    mp1[s.at(i)]++;
    mp2[k.at(i)]++;
  }
  
  ll ans = (mp1.size() * h) + (mp2.size() * w) - (mp1.size() * mp2.size()) - n;
  cout << ans << '\n';
}