#include <bits/stdc++.h>
using namespace std;
int maxx[40007];
int maxy[40007];
int c[40007];
int d[40007];
long long res=0, n, m, x, y, k, mx, all;
int main ()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin>>n>>m>>k;
    for (int i=1; i<=k; i++)
        cin>>c[i]>>d[i];
    c[k+1]=0;
    c[k+2]=n+1;
    d[k+1]=0;
    d[k+2]=m+1;
    k+=2;
    sort(c+1, c+1+k);
    sort(d+1, d+1+k);
    for (int i=1; i<=k; i++) {
        maxx[i]=c[i+1]-c[i];
        maxy[i]=d[i+1]-d[i];
        all=maxx[i]*maxy[i];
        if (all>mx) mx=all;
    }
    cout<<mx;
}