def check(i, j, k):
    if i + j > X[k] + Y[k]:
        return 0
    if i - j > X[k] - Y[k]:
        return 0
    return 1
    
    

H, W, K = map(int, input().split())
mod = 998244353
X, Y, V = [0] * K, [0] * K, [0] * K
for i in range(K):
    X[i], Y[i], V[i] = map(int, input().split())
    X[i], Y[i] = X[i] - 1, Y[i] - 1
    
ans = 0
for i in range(H):
    for j in range(W):
        for k in range(K):
            if check(i, j, k):
                ans += V[k]
                ans %= mod
print(ans)