MOD = 998244353

def main():
    import sys
    N, M = map(int, sys.stdin.readline().split())
    if M == 0:
        print(0)
        return
    
    max_m = M
    # Precompute factorials and inverse factorials
    max_fact = max(2*M, N)
    fact = [1]*(max_fact+1)
    inv_fact = [1]*(max_fact+1)
    for i in range(1, max_fact+1):
        fact[i] = fact[i-1] * i % MOD
    inv_fact[max_fact] = pow(fact[max_fact], MOD-2, MOD)
    for i in range(max_fact-1, -1, -1):
        inv_fact[i] = inv_fact[i+1] * (i+1) % MOD
    
    def comb(m, s):
        if s < 0 or s > m:
            return 0
        return fact[m] * inv_fact[s] % MOD * inv_fact[m-s] % MOD
    
    total = 0
    
    # Process m from 1 to M-1
    for m in range(1, M):
        current = 0
        x = 2 * M - 1
        for s in range(0, m+1):
            c = comb(m, s)
            term = pow(x - s, N, MOD)
            if s % 2 == 1:
                term = (-term) % MOD
            current = (current + c * term) % MOD
        total = (total + m * current) % MOD
    
    # Process m = M
    m = M
    current = 0
    x = 2 * M
    for s in range(0, m+1):
        c = comb(m, s)
        term = pow(x - s, N, MOD)
        if s % 2 == 1:
            term = (-term) % MOD
        current = (current + c * term) % MOD
    total = (total + m * current) % MOD
    
    print(total % MOD)

if __name__ == '__main__':
    main()