#include <bits/stdc++.h>
using namespace std;
//#include <atcoder/all>
//using namespace atcoder;
using ll=long long;
using Graph=vector<vector<int>>;
#define MAX 1000000
//#define MOD 1000000007
#define MOD 998244353
//#define INF 1000000000
#define INF 1000000000000000000

int main(){
  int W,H,N;
  cin>>W>>H>>N;
  vector<int> S(N),K(N);
  for(int i=0;i<N;i++){
    cin>>S[i]>>K[i];
    S[i]--;K[i]--;
  }
  vector<int> cnt1(W,H),cnt2(H,W);
  for(int i=0;i<N;i++){
    cnt1[S[i]]--;
    cnt2[K[i]]--;
  }
  ll ans=0;
  vector<int> w,h;
  for(int i=0;i<W;i++){
    if(cnt1[i]<H){
      ans+=(ll)cnt1[i];
      w.push_back(i);
    }
  }
  for(int i=0;i<H;i++){
    if(cnt2[i]<W){
      ans+=(ll)cnt2[i];
      h.push_back(i);
    }
  }
  for(auto a:w){
    for(auto b:h){
      bool flag=true;
      for(int i=0;i<N;i++){
        if(S[i]==a&&K[i]==b){
          flag=false;
        }
      }
      if(flag==true){
        ans--;
      }
    }
  }
  cout<<ans<<endl;
}