import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
sys.setrecursionlimit(10**7)
yes = lambda :print("yes");Yes = lambda :print("Yes")
no = lambda :print("no");No = lambda :print("No")

n,m = na()
mod = 998244353
z = [pow(i,n,mod) for i in range(m+1)]
d2 = pow(2,mod-2,mod)
def g(x):
    return ((z[x]*(x+1)*d2)%mod)*n%mod

def h(x):
    return ((z[m-x+1]*(m+x)*d2)%mod)*n%mod
ans = 0
for k in range(1,m+1):
    #print(g(k)-g(k-1),h(k)-h(k+1))
    ans+=k*(g(k)-g(k-1))%mod
    ans%=mod
    ans-=k*(h(k)-h(k+1))%mod
    ans%=mod
print(ans)