#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <string>
#include <queue>
#include <stack>
#include <math.h>
#include <set>
#define ALL(obj) (obj).begin(),(obj).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()
#define P pair<int, int>

#define MOD 1000000007
#define INF 1012345678
#define NINF (-2147483647-1)
#define LLINF 9223372036854775807
using ll = long long;
using namespace std;

int main() {
    int W, H, N;
    cin >> W >> H >> N;
    ll cnt = 0;
    set<int> w, h;
    for (int i = 0; i < N; i++)
    {
        int S, K;
        cin >> S >> K;
        if (w.find(S) == w.end() && h.find(K) == h.end()) {
            cnt += H - 1 + W - 1 - h.size() - w.size();
            w.insert(S);
            h.insert(K);
        }
        else if (w.find(S) == w.end()) {
            cnt += H - 1 - h.size();
            w.insert(S);
        }
        else if (h.find(K) == h.end()) {
            cnt += W - 1 - w.size();
            h.insert(K);
        }
        else {
            cnt--;
        }
    }
    cout << cnt << endl;
    getchar(); getchar();
    return 0;
}