#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    ll W, H, N;
    cin >> W >> H >> N;
    int w[W] = {};
    int h[H] = {};
    int s[N], k[N];
    
    rep(i,N){
        cin >> s[i] >> k[i];
        s[i]--; k[i]--;
        w[s[i]] = 1;
        h[k[i]] = 1;
    }

    ll ans = 0;
    ll cnt1 = 0;
    ll cnt2 = 0;
    rep(i,W)cnt1 += w[i];
    rep(i,H)cnt2 += h[i];

    ans = cnt1 * H + cnt2 * W - N - cnt1 * cnt2;

    cout << ans << endl;
    return 0;
}