#include<bits/stdc++.h>
using namespace std;

using ll=long long;

int main(){cin.tie(0);ios::sync_with_stdio(false);
	ll W,H;cin>>W>>H;
	int N;cin>>N;
	vector<ll>x(N),y(N);
	bool o=true;
	for(int i=0;i<N;++i){
		cin>>x[i]>>y[i];
		o&=(x[i]+y[i])%2==(x[0]+y[0])%2;
	}
	ll z=0;
	if(o){
		for(int _=0;_<2;++_){
			for(int _=0;_<4;++_){
				ll mx=2e9,MX=-2e9;
				ll my=2e9,MY=-2e9;
				ll mp=2e9,MP=-2e9;
				ll mm=2e9,MM=-2e9;
				for(int i=0;i<N;++i){
					mx=min(mx,x[i]);
					MX=max(MX,x[i]);
					my=min(my,y[i]);
					MY=max(MY,y[i]);
					mp=min(mp,x[i]+y[i]);
					MP=max(MP,x[i]+y[i]);
					mm=min(mm,x[i]-y[i]);
					MM=max(MM,x[i]-y[i]);
				}
				if(N==2){
					if(mp==MP){
						z=max(z,mx*my+(W-MX+1)*(H-MY+1)+MX-mx-1);
					}else if(MX-mx<MY-my){
						z=max(z,W);
					}
				}else{
					bool a=mp==MP;
					bool b=true;
					bool c=MP-mp>=MM-mm;
					bool d=c;
					bool e=MP-mp==MM-mm;
					int k=-1;
					ll m=2e9;
					for(int i=0;i<N;++i){
						b&=x[i]+y[i]==MP||x[i]-y[i]==MM;
						c&=x[i]+y[i]==MP^x[i]+y[i]==mp;
						d&=x[i]+y[i]==MP||x[i]+y[i]==mp||x[i]-y[i]==MM;
						e&=x[i]+y[i]==MP||x[i]+y[i]==mp||x[i]-y[i]==MM||x[i]-y[i]==mm;
						if(x[i]+y[i]==MP){
							m=min(m,x[i]);
						}else{
							if(k==-1){
								k=i;
							}else{
								k=-2;
							}
						}
					}
					if(a)z=max(z,mx*my+(W-MX+1)*(H-MY+1));
					if(b)z=max(z,mx);
					if(c)z=max(z,((MP-mp)-(MM-mm))/2+1);
					if(d)z=max(z,1ll);
					if(e)z=max(z,1ll);
					if(k>=0&&x[k]-y[k]==MM)z=max(z,m);
				}
				for(int i=0;i<N;++i){
					ll t=x[i];
					x[i]=H-y[i]+1;
					y[i]=t;
				}
				swap(W,H);
			}
			for(int i=0;i<N;++i){
				y[i]=H-y[i]+1;
			}
		}
	}
	cout<<z<<"\n";
	return 0;
}