#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
using T = tuple<int, int, int>;
#define al(a) a.begin(), a.end()
#define ral(a) a.rbegin(), a.rend()
#define sz(a) (int)a.size()
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rrep(i, n) for (int i = 1; i <= (n); ++i)
#define drep(i, n) for (int i = (n)-1; i >= 0; --i)
#define db(a, b) cout << #a << ": " << a << " " << #b << ": " << b << endl;

int main() {
  int h, w, n;
  cin >> h >> w >> n;
  set<int> y;
  map<int, vector<int>> mp;
  rep(i, n) {
    int s, k;
    cin >> s >> k;
    mp[s].push_back(k);
    y.insert(k);
  }
  ll ans = 0;
  for (auto [s, ls] : mp) { ans += w - sz(ls); }
  ans += (h - sz(mp)) * sz(y);
  cout << ans << endl;
  return 0;
}