MOD = 998244353

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

# Precompute binomial coefficients C[k][t] for 0 <= t <=k <=N
C = []
for k in range(N + 1):
    row = [0] * (k + 1)
    row[0] = 1
    if k >= 1:
        row[k] = 1
    for t in range(1, k):
        row[t] = (C[k-1][t-1] + C[k-1][t]) % MOD
    C.append(row)

M_mod = M % MOD

ans = 0
for k in range(1, N + 1):
    sum_k = 0
    base = (2 * M_mod + 1) % MOD
    for t in range(0, k + 1):
        current_base = (base - t) % MOD
        pow_val = pow(current_base, N, MOD)
        sign = 1 if t % 2 == 0 else MOD - 1
        term = (sign * C[k][t]) % MOD
        term = (term * pow_val) % MOD
        sum_k = (sum_k + term) % MOD
    sum_k = (sum_k * k) % MOD
    ans = (ans + sum_k) % MOD

print(ans)