#include <iostream>
#include <map>
#include <set>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
    long long h,w,n;cin>>h>>w>>n;
    map<long long,long long> M;
    map<long long,long long> V;
    set<long long> Ms;
    set<long long> Vs;
    vector<pair<long long,long long> > A(n);
    for(int i = 0; n > i; i++){
        long long a,b;cin>>a>>b;
        M[a]++;
        V[b]++;
        Ms.insert(a);
        Vs.insert(b);
        A[i].first = a;
        A[i].second = b;
    }
    long long ans = 0;
    for(auto x: M){
        ans += w-x.second;
    }
    for(auto x: V){
        ans += h-x.second;
    }
    for(auto x: Ms){
        for(auto y: Vs){
            bool t = true;
            for(int i = 0; n > i; i++){
                if(x == A[i].first && y == A[i].second){
                    t = false;
                    break;
                }
            }
            ans -= t;
        }
    }
    cout << ans << endl;
    
}