# この制約なら単純全探索でもO(HWK) ~50**4 ~6.25*10**4

mod = 998244353

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

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
                ans %= mod

print(ans)