from sys import stdin
import sys
import math

mod = 998244353
def inverse(x):
    return pow(x,mod-2,mod)
half = inverse(2)


N,M = map(int,stdin.readline().split())
ans = 0

dp = []

nowok = 0

for K in range(M):

    a = M-K
    if K != 0:
        nowok += pow(K,N,mod) - pow(K-1,N,mod)
    else:
        nowok += pow(K,N,mod)
    nowok %= mod

    other = (pow(K+1,N,mod) - pow(K,N,mod)) * (M-K)

    dp.append((nowok + other) % mod)

dp.append(0)
ans = 0
for K in range(M):
    ans += (dp[K]-dp[K-1]) * K

print (ans * (M+1) * N * half % mod)