n, m = map(int, input().split())
res, mod = 0, 998244353
for r in range(1, m + 1):
    res += (pow(r, n, mod) - pow(r - 1, n, mod)) * r
    res %= mod
for l in range(1, m + 1):
    res -= (pow(m - l + 1, n, mod) - pow(m - l, n, mod)) * l
    res %= mod
res *= n
res %= mod
res *= m + 1
res %= mod
res *= 499122177
res %= mod
print(res)