MOD = 998244353

N, M = map(int, input().split())

max_v = N + 1

# Precompute factorial and inverse factorial up to max_v
fact = [1] * (max_v + 1)
for i in range(1, max_v + 1):
    fact[i] = fact[i-1] * i % MOD

inv_fact = [1] * (max_v + 1)
inv_fact[max_v] = pow(fact[max_v], MOD-2, MOD)
for i in range(max_v-1, -1, -1):
    inv_fact[i] = inv_fact[i+1] * (i+1) % MOD

def comb(v, k):
    if k < 0 or k > v:
        return 0
    return fact[v] * inv_fact[k] % MOD * inv_fact[v - k] % MOD

total = 0
for v in range(1, N + 2):
    sum_inner = 0
    for k in range(0, v + 1):
        c = comb(v, k)
        exponent_base = (1 + 2 * M - v + k) % MOD
        pow_val = pow(exponent_base, N, MOD)
        sign = pow(-1, v - k, MOD)
        term = c * sign % MOD
        term = term * pow_val % MOD
        sum_inner = (sum_inner + term) % MOD
    total = (total + v * sum_inner) % MOD

print(total % MOD)