MOD=998244353
N=int(input())
s=input()
dp=[0,1]
for i in range(N):
	ndp=[0]*(i+3)
	cum=[0]*(i+4)
	for j in range(i+2):
		dp[j]%=MOD
		if s[i]=="1":
			ndp[j+1]+=dp[j]*j
		else:
			ndp[j]+=dp[j]*(i+1-j)
			cum[j+1]-=dp[j]
			cum[1]+=dp[j]
	for j in range(1,i+4):
		cum[j]+=cum[j-1]
		ndp[j-1]+=cum[j-1]
	dp=ndp
print(sum(dp)%MOD)