#include <bits/stdc++.h>
#define REP(i,n) for(int i = 0; i < (int)(n); ++i)
using namespace std;

int main() {
    long long W, H, N;
    cin >> W >> H >> N;
    vector<int> S, K;
    long long t, l;
    REP(i,N){
        cin >> t >>l;
        S.push_back(t);
        K.push_back(l);
    }
    sort(S.begin(),S.end());
    sort(K.begin(),K.end());
    long long cs = 1;
    long long ck = 1;
    long long ss = 0;
    long long sk = 0;
    REP(i,N-1){
        if(S[i]<S[i+1]) cs++;
        if(S[i]==S[i+1]) ss++;
        if(K[i]<K[i+1]) ck++;
        if(K[i]==K[i+1]) sk++;
    }

    cout << (H-ck)*cs + (W-cs)*ck + (cs*ck-max(ck,cs)-min(sk,ss)) << endl;
    return 0;
}