#pragma GCC target("avx512vl")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#include <atcoder/dsu>
using namespace atcoder;

bitset<5064> dp[5000+1];
#pragma clang attribute push(__attribute__((target ("avx,avx2"))),apply_to=function)
int main() {
    int H, W, N; cin >> H >> W >> N;
    atcoder::dsu d(H+W);
    for (int i = 0; i < N; i++) {
        int a, b; cin >> a >> b;
        a--; b--;
        d.merge(a, b+H);
    }
    vector<vector<int>> G = d.groups();
    int K = (int)G.size();
    dp[0][0] = 1;
    int rcsum = 0;
    for (int i = 0; i < K; i++) {
        vector<int> g = G[i];
        int rcnt = 0, ccnt = 0;
        for (int v : g) {
            if (v < H) rcnt++;
            else ccnt++;
        }
        for (int j = rcsum; j >= 0; j--) {
            dp[j+rcnt]|=(dp[j]<<ccnt);
        }
        rcsum += rcnt;
    }
    int ans = 0;
    for (int i = 0; i <= H; i++) {
        for (int j = 0; j <= W; j++) {
            if (dp[i][j]) {
                ans = max(ans, i*(W-j)+(H-i)*j);
            }
        }
    }
    cout << ans << endl;
}
#pragma clang attribute pop