from sys import stdin
input = stdin.readline

MOD = 998244353

H, W, K = map(int, input().split())
A = [list(map(int, input().split())) for _ in range(K)]

ans = 0
for h, w, v in A:
    h, w = h-1, w-1
    for i in range(H):
        for j in range(W):
            if i <= h and abs(j-w) <= h-i:
                ans += v
                ans %= MOD

print(ans)