H, W, K = map(int, input().split())
x = []
y = []
v = []
for i in range(K):
    X, Y, V = map(int, input().split())
    x.append(X - 1)
    y.append(Y - 1)
    v.append(V)
ans = 0
mod = 998244353

for i in range(H):
    for j in range(W):
        for k in range(K):
            if x[k] + y[k] >= i + j and x[k] - y[k] >= i - j:
                ans = (ans + v[k]) % mod
print(ans)