MOD = 998244353

def main():
    import sys
    N, M = map(int, sys.stdin.readline().split())
    max_m = min(N, M + 1)
    
    # Precompute binomial coefficients up to max_m
    comb = [[0] * (max_m + 1) for _ in range(max_m + 1)]
    comb[0][0] = 1
    for m in range(1, max_m + 1):
        comb[m][0] = 1
        for k in range(1, m + 1):
            comb[m][k] = (comb[m-1][k-1] + comb[m-1][k]) % MOD
    
    total = 0
    for m in range(1, max_m + 1):
        sum_terms = 0
        for k in range(0, m + 1):
            sign = 1 if k % 2 == 0 else MOD - 1
            c = (comb[m][k] * sign) % MOD
            x = (2 * M + 1 - k) % MOD
            x_pow = pow(x, N, MOD)
            term = (c * x_pow) % MOD
            sum_terms = (sum_terms + term) % MOD
        contribution = (m * sum_terms) % MOD
        total = (total + contribution) % MOD
    print(total)

if __name__ == "__main__":
    main()