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

n, m = LI()
ss = [[0]*(n+2) for _ in range(m+1)]
dp = [0]*(n+2)
dp[1] = 1

for i in range(n):
    for a in range(1, m+1):
        l = max(i+2-a, 0)
        val = dp[i+1]-dp[l]-(ss[a][i+1]-ss[a][l])
        val %= md
        ss[a][i+2] = (ss[a][i+1]+val)%md
        dp[i+2] += val
        dp[i+2] %= md
    dp[i+2] = (dp[i+2]+dp[i+1])%md

ans = pow(m, n, md)-(dp[n+1]-dp[n])

print(ans%md)