import sys
input = lambda : sys.stdin.readline().rstrip()

sys.setrecursionlimit(2*10**5+10)
write = lambda x: sys.stdout.write(x+"\n")
debug = lambda x: sys.stderr.write(x+"\n")
writef = lambda x: print("{:.12f}".format(x))


n,m = list(map(int, input().split()))
M = 998244353
ans = 0
inv2 = pow(2, M-2, M)
def f(v):
    return inv2 * (n * ((v+1) * pow(v, n, M) % M) % M) % M
def g(v):
    return inv2 * ((m + v) * (n * pow(m-v+1, n, M) % M) % M) % M
for v in range(1,m+1):
    ans += v * (f(v) - f(v-1)) % M
    ans -= v * (g(v) - g(v+1)) % M
    ans %= M
print(ans%M)