P8848

#include<bits/stdc++.h>
using namespace std;
const int mod=998244353;
int C(int a,int b){
	int res=1;
	for(int i=a;i>a-b;i--)res=1ll*res*i%mod;
	for(int i=b;i;i--)res/=i;
	return res;
}
vector<int> dp[10005];
int main(){
	int n,cnt1=0,cnt2=0; 
	cin>>n;
	for(int x,i=1;i<=n;i++)cin>>x,x==1?cnt1++:cnt2++;
	if(cnt1<=cnt2)return cout<<C(cnt2+1,cnt1),0;
	dp[0].push_back(1);
	for(int i=0;i<=cnt1;i++){
		for(int j=0;j<=cnt2;j++)
			if(i>=j&&i-j<=cnt1-cnt2){
				int tmp=0;
				if(i)tmp+=dp[i-1][j];
				if(j)tmp+=dp[i][j-1];
				if(tmp)dp[i].push_back(tmp%mod);
			}else dp[i].push_back(0);
	}	
	return cout<<dp[cnt1][cnt2],0;
}