import sys,random,bisect
from collections import deque,defaultdict
from heapq import heapify,heappop,heappush
from itertools import permutations
from math import gcd,log

input = lambda :sys.stdin.readline().rstrip()
mi = lambda :map(int,input().split())
li = lambda :list(mi())

H,W,K = mi()
tre = [tuple(mi()) for i in range(K)]

res = 0
for i in range(1,H+1):
    for j in range(1,W+1):
        for x,y,v in tre:
            if x+y >= i+j and x-y >= i-j:
                res += v

print(res % 998244353)