MOD = 998244353

def main():
    import sys
    N, M = map(int, sys.stdin.readline().split())
    
    # Precompute combinations up to 2000
    max_k = min(N, M + 1)
    comb = [[0] * (2001) for _ in range(2001)]
    comb[0][0] = 1
    for k in range(1, 2001):
        comb[k][0] = 1
        comb[k][k] = 1
        for s in range(1, k):
            comb[k][s] = (comb[k-1][s-1] + comb[k-1][s]) % MOD
    
    total = 0
    k_max = min(N, M + 1)
    for k in range(1, k_max + 1):
        if (k - 1) > M:
            continue
        
        if M >= k:
            b = (1 + 2 * (M - k)) % MOD
        else:
            b = 0
        
        sum_s = 0
        for s in range(0, k + 1):
            c = comb[k][s]
            base = (k + b + s) % MOD
            power = pow(base, N, MOD)
            
            # Compute (-1)^(k - s)
            exponent = k - s
            if exponent % 2 == 0:
                sign = 1
            else:
                sign = MOD - 1
            
            term = (c * power) % MOD
            term = (term * sign) % MOD
            sum_s = (sum_s + term) % MOD
        
        contribution = (k * sum_s) % MOD
        total = (total + contribution) % MOD
    
    print(total)

if __name__ == "__main__":
    main()