MOD=998244353
N,M=map(int,input().split())
ans=0
for i in range(min(N,M+1)+1):
	dp=[1]
	for j in range(N):
		ndp=[0]*(j+2)
		for k in range(j+1):
			dp[k]%=MOD
			ndp[k]+=dp[k]*(M-i+k)
			ndp[k+1]+=dp[k]*(i-k)
		dp=ndp
	ans+=dp[i]*i*i
	ans%=MOD
print(ans)