using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    static long[][] 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;
        foreach (var tr in map)
        {
            var count = tr[0] * tr[0];
            var left = tr[1] - tr[0];
            var ltri = left < 1 ? ((1 - left) * (0 - left) / 2) : 0;
            var right = tr[1] + tr[0];
            var rtri = right > w ? ((right - w) * (right - w - 1) / 2) : 0;
            ans = (ans + (count - ltri - rtri) % mod * tr[2] % mod) % mod;
        }
        WriteLine(ans);
    }
}