#include <iostream>
using namespace std;

#define fastcin {\
    cin.tie(0);\
    ios::sync_with_stdio(false);\
}
#define REP(i, a) for(int i = 0; i < a; i++)
#define scan(x) cin >> x
#define print(x) cout << x << "\n"

typedef long long ll;


int main() {
    fastcin;
    int W, H;
    ll N;
    scan(W); scan(H); scan(N);

    bool wl[1000001] = {}, hl[1000001] = {};
    int wa = 0, ha = 0;
    ll ans;
    REP(i, N) {
        int s, k;
        cin >> s >> k;
        if (!wl[s]) {
            wa++;
            wl[s] = true;
        } else ;
        if (!hl[k]) {
            ha++;
            hl[k] = true;
        } else ;
    }
    ans = wa*H + ha*W - N - wa*ha;
    print(ans);

    return 0;
}