#include<iostream>
#include<iomanip>
#include<string>
#include<algorithm>
#include<vector>
#include<set>
#include<list>
#include<queue>
#include<math.h>
#include<bitset>
using ll = long long;
using namespace std;

int main(){
    int w, h, n, ans = 0;
    cin >> w >> h >> n;
    int suit_n = w, num_n = h;
    vector<int> suit(w), num(h);
    for (int i = 0; i < n; i++){
        int s, k;
        cin >> s >> k;
        if (suit[s-1]){
            if (!num[k-1]){
                ans--;
                num[k]++;
                num_n--;
                ans += suit_n;
            } 
        } else {
            if (num[k-1]){
                ans--;
                suit[s-1]++;
                suit_n--;
                ans += num_n;
            } else {
                suit[s-1]++;
                num[k-1]++;
                num_n--;
                suit_n--;
                ans += (num_n + suit_n);
            }
        }
    }
    cout << ans << endl;
}