#include <bits/stdc++.h>

using namespace std;

#define DIM 103
#define INF 1000000


long long x,y,n;
long long m,x1,yy1;

long long maxXY,all;
int main()
{

        cin>>x>>y>>n;
        long long x_visited[x+12];
        long long y_visited[y+12];
        long long together_x[x+x];
        long long together_y[y+y];

        x_visited[n+1]=0;
        y_visited[n+1]=0;
        x_visited[n+2]=x+1;
        y_visited[n+2]=y+1;
    for(int i=1;i<=n;i++){
        cin>>x1>>yy1;
        x_visited[yy1]=x1;
        y_visited[yy1]=yy1;

    }
    sort(x_visited+1,x_visited+1+n);
    sort(y_visited+1,y_visited+1+n);
    for(int i=1;i<n;i++){
        together_x[i]=x_visited[i+1]-x_visited[i];
        together_y[i]=y_visited[i+1]-y_visited[i];
        all=together_y[i]*together_x[i];

        if(all>maxXY){
            maxXY=all;
        }
    }
    cout<<maxXY<<endl;
    return 0;
}