using LIB;
using System;
using System.Linq;
using System.Text;
using System.Collections.Generic;

class Program
{
    public static IO IO = new IO();
    static void Main(string[] args)
    {
        int[] n = IO.INT(' ');
        int[][] m = IO.INT(n[2], ' ');
        bool[,] b = new bool[n[0], n[1]];
        for (int i = 0; i < n[2]; i++)
        {
            int[] buf = m[i];
            if (buf[2] == 1)
            {
                for (int j = 0; j < buf[0]; j++)
                {
                    for (int k = 0; k < n[1]; k++)
                    {
                        b[j,k] = true;
                    }
                }
            }
            else if (buf[2] == 2)
            {
                for (int j = buf[0]; j < n[0]; j++)
                {
                    for (int k = 0; k < n[1]; k++)
                    {
                        b[j, k] = true;
                    }
                }
            }
            else if (buf[2] == 3)
            {
                for (int j = 0; j < n[0]; j++)
                {
                    for (int k = 0; k < buf[1]; k++)
                    {
                        b[j, k] = true;
                    }
                }
            }
            else
            {
                for (int j = 0; j < n[0]; j++)
                {
                    for (int k = buf[1]; k < n[1]; k++)
                    {
                        b[j, k] = true;
                    }
                }
            }
        }
        int c = 0;
        for (int i = 0; i < n[0]; i++)
        {
            for (int j = 0; j < n[1]; j++)
            {
                if (!b[i, j]) { c++; }
            }
        }
        IO.WRITE(c);
        IO.FLUSH();
    }
}

namespace LIB
{
    public class IO
    {
        private const int WMAX = 1000;
        private StringBuilder S = new StringBuilder();
        private T R<T>(Func<string, T> f) { return f(Console.ReadLine()); }
        private T[] R<T>(Func<string, T> f, char c) { return STRING().Split(c).Select(f).ToArray(); }
        private T[] R<T>(Func<string, T> f, int l) { T[] r = new T[l]; for (int i = 0; i < l; i++) { r[i] = R(f); } return r; }
        private T[][] R<T>(Func<string, T> f, int l, char c) { T[][] r = new T[l][]; for (int i = 0; i < l; i++) { r[i] = R<T>(f, c); } return r; }
        private void W<T>(Func<T, string> f, T v, bool lf = true) { S.Append(f(v)); if (lf) { S.Append('\n'); } if (S.Length >= WMAX) { FLUSH(); } }
        public string STRING() { return R(s => s); }
        public string[] STRING(char c) { return R(s => s, c); }
        public string[] STRING(int l) { return R(s => s, l); }
        public string[][] STRING(int l, char c) { return R(s => s, l, c); }
        public int INT() { return R(int.Parse); }
        public int[] INT(char c) { return R(int.Parse, c); }
        public int[] INT(int l) { return R(int.Parse, l); }
        public int[][] INT(int l, char c) { return R(int.Parse, l, c); }
        public long LONG() { return R(long.Parse); }
        public long[] LONG(char c) { return R(long.Parse, c); }
        public long[] LONG(int l) { return R(long.Parse, l); }
        public long[][] LONG(int l, char c) { return R(long.Parse, l, c); }
        public double DOUBLE() { return R(double.Parse); }
        public double[] DOUBLE(char c) { return R(double.Parse, c); }
        public double[] DOUBLE(int l) { return R(double.Parse, l); }
        public double[][] DOUBLE(int l, char c) { return R(double.Parse, l, c); }
        public void WRITE(object s, bool lf = true) { W(v => v.ToString(), s, lf); }
        public void FLUSH() { Console.Write(S); S.Length = 0; }
    }
}

Measured memory_bytes: 3160