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

typedef long long ll;

int main() {
    ll W,H,N;
    cin >> W >> H >> N;
    vector<ll> S(N), K(N);
    map<ll,ll> m;
    set<ll> s;
    for(int i=0; i<N; i++){
        cin >> S[i] >> K[i];
        m[S[i]]++;
        s.insert(K[i]);
    }
    ll ans=0;
    for(auto itr=m.begin(); itr!=m.end(); itr++){
        //cout << itr->first <<" "<< itr->second << endl;
        ans += H-itr->second;
    }

    cout << ans + (W-m.size())*s.size() << endl;



}