#include <bits/stdc++.h>

using namespace std;
set < pair < long long, long long > > s;
pair < long long, long long > p;
long long n,i,res,k,x[40001],y[40001],w,h,mx,my;

int main()
{
    cin >> w >> h >> n;
    for(i=1;i<=n;i++){
        cin >> x[i] >> y[i];
        }
        n+=2;
        x[n+1] = 0;
        x[n+2] = w+1;
        y[n+1] = 0;
        y[n+2] = h+1;
        sort(x+1,x+n+1);
        sort(y+1,y+n+1);
        for(i=2;i<=n;i++){
            if(x[i]-x[i-1]>mx)mx=x[i]-x[i-1];
            if(y[i]-y[i-1]>my)my=y[i]-y[i-1];
        }
    cout << mx*my;
    return 0;
}