using System;
using System.Linq;
using System.Collections.Generic;

class No11{
    static void Main(){
       var W=Int32.Parse(Console.ReadLine());
       var H=Int32.Parse(Console.ReadLine());
       var N=Int32.Parse(Console.ReadLine());
       var wList=new List<int>();
       var hList=new List<int>();
       var ans=0;
       for(int i=0;i<N;++i){
           var line=Console.ReadLine().Split(' ').Select(x=>Int32.Parse(x)).ToArray();
           if(!wList.Contains(line[0])){
               if(hList.Contains(line[1]))ans+=H-1;
               else ans+=(H-1)-wList.Distinct().Count();
           }else{
            ans--;
            }
           if(!hList.Contains(line[1])){
                if(wList.Contains(line[0]))ans+=W-1;
               else ans+=(W-1)-hList.Distinct().Count();
           }
           else{ ans--;
           }
       }
       Console.WriteLine(ans);
       
    }
}