import sys

# sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = (1 << 63)-1
# inf = (1 << 31)-1
# md = 10**9+7
md = 998244353

from functools import lru_cache

inv = (md+1)//2
n, m = LI()

# 最大値がk以下の数列の和
@lru_cache(None)
def f(k):
    return n*pow(k, n-1, md)%md*k%md*(k+1)%md*inv%md
# 最小値がk以上の数列の和
@lru_cache(None)
def g(k):
    return n*pow(m-k+1, n-1, md)%md*(m+k)%md*(m-k+1)%md*inv%md

ans = 0
for k in range(1, m+1):
    ans += k*(f(k)-f(k-1)-g(k)+g(k+1))
    ans %= md

print(ans)