#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ul;
typedef signed long long ll;
ul over = 1000000007;

int main(void)
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed;
  ll w, h, n;
  cin >> w >> h >> n;
  ll ts[n], tk[n];
  for (ll i = 0; i < n; ++i) cin >> ts[i] >> tk[i];
  ll wline = 0, hline = 0;
  ll ans = 0;
  for (ll i = 0; i < n; ++i) {
    bool whit = false, hhit = false;
    for (ll j = 0; j < i; ++j) {
      if (ts[i] == ts[j]) whit = true;
      if (tk[i] == tk[j]) hhit = true;
    }
    if (!whit && !hhit) {
      wline++; hline++;
      ans += (w-wline) + (h-hline);
    } else if (!whit) {
      wline++;
      ans += (h-hline);
      ans--;
    } else if (!hhit) {
      hline++;
      ans += (w-wline);
      ans--;
    } else {
      ans--;
    }
  }
  cout << ans << endl;
  return 0;
}