N,M=map(int,input().split())
mod=998244353

ANS=0
INV=pow(2,mod-2,mod)

for s in range(M):
    ko=(pow(s+1,N,mod)-pow(s,N,mod)*2+pow(s-1,N,mod))*(M-s)
    ANS+=ko*s*((1+1+s)+(M+M-s))*N*INV*INV
    ANS%=mod

print(ANS)