using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;
class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (h, w, k) = (c[0], c[1], c[2]);
        var map = NArr(k);
        var ans = 0L;
        var mod = 998_244_353;
        for (var i = 1; i <= h; ++i) for (var j = 1; j <= w; ++j)
        {
            foreach (var g in map)
            {
                if (g[0] + g[1] >= i + j && g[0] - g[1] >= i - j) ans = (ans + g[2]) % mod;
            }
        }
        WriteLine(ans);
    }
}