#include<bits/stdc++.h>
using namespace std;
const int mod=998244353;
int n,dp[2005][2005],q[2005][2005],ans;
string s;
int main(){
   // freopen("aspect.in","r",stdin);
   // freopen("aspect.out","w",stdout);
    cin>>n;
    cin>>s;
    s=' '+s;
    dp[0][0]=1;
    q[0][0]=1;
    for(int i=1;i<=n;i++){
        for(int j=0;j<=i;j++){
            q[i][j]+=q[i][j-1];  
            if(s[i]=='0'){
                if(j){
                    dp[i][j]=q[i-1][j-1];
                }
                if(j>1)dp[i][j]+=dp[i-1][j-1]*1ll*(j-1)%mod;
                dp[i][j]%=mod;
            }
            else{
                dp[i][j]+=dp[i-1][j]*1ll*(i-j)%mod;
            }
            q[i][j]+=dp[i][j];
            q[i][j]%=mod;
        }
    }
    cout<<q[n][n]<<'\n';
    return 0;
}