import sys
from sys import stdin

H,W,K = map(int,stdin.readline().split())

xyv = []

for i in range(K):

    x,y,v = map(int,stdin.readline().split())
    xyv.append( (x,y,v) )

ans = 0
for i in range(1,H+1):

    for j in range(1,W+1):

        for x,y,v in xyv:

            if x+y >= i+j and x-y >= i-j:
                ans += v

print (ans % 998244353)