N,K=list(map(int,input().split()))
A=list(map(int,input().split()))
B=list(map(int,input().split()))
dp=[]
MOD=998244353
for i in range(N+1):
	d=[]
	for j in range(N+1):
		d.append([0]*(N+1))
	dp.append(d)
dp[0][0][0]=1
for i in range(N):
	for j in range(N):
		for k in range(N):
			dp[i+1][max(j,k+1)][k+1]=(dp[i+1][max(j,k+1)][k+1]+dp[i][j][k]*A[i])%MOD
			dp[i+1][j][0]=(dp[i+1][j][0]+dp[i][j][k]*B[i])%MOD
ans=0
for i in range(N+1):
	ans=(ans+dp[N][K][i])%MOD
print(ans)