#include <bits/stdc++.h>
#define rep(i, n) for(long long i = 0; i < n; i++)
#define ALL(v) (v).begin(), (v).end()
using namespace std;

using lint = long long;

int main() {
    lint w, h, n;
    cin >> w >> h >> n;
    vector<lint> gyo(w, 0), retsu(h, 0);
    rep(i, n) {
        int s, k;
        cin >> s >> k;
        s--;
        k--;
        gyo[s]++;
        retsu[k]++;
    }
    lint ans = 0;
    rep(i, w) {
        if (gyo[i] > 0) {
            ans += h - gyo[i];
        }
    }
    lint cnt = 0;
    rep(i, w) {
        if (gyo[i] == 0) {
            cnt++;
        }
    }
    rep(i, h) {
        if (retsu[i] > 0) {
            ans += cnt;
        }
    }
    cout << ans << endl;
}