#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <cmath>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <bitset>
using namespace std;

#define PI         acos(-1.0)
#define FOR(I,A,B) for(int I = (A); I < (B); ++I)

typedef long long ll;

int main(){
    int h, w, n;
    cin >> w >> h >> n;
    ll s[n], k[n];
    bool p[w+1][h+1];
    int nr[w+1], nl[h+1];
    int cntr = 0, cntl = 0;
    FOR(i,0,w+1) nr[i] = 0;
    FOR(i,0,h+1) nl[i] = 0;
    FOR(i,0,w+1) FOR(j,0,h+1) p[i][j] = false;
    FOR(i,0,n){
        cin >> s[i] >> k[i];
        p[s[i]][k[i]] = true;
        nr[s[i]]++;
        nl[k[i]]++;
    }
    FOR(i,0,w+1) if(nr[i]!=0) cntr++;
    FOR(i,0,h+1) if(nl[i]!=0) cntl++;

    ll ans = h * cntr - n + w * cntl - n;
    ll hiku = 0;
    FOR(i,0,n){
        FOR(j,0,n){
            if(i==j) continue;
            if(!p[s[i]][k[j]]) hiku++;
        }
    }

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