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

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

    }
}