#include<bits/stdc++.h>
using namespace std;
const int mod = 998244353;
int n;string s;
const int N = 3005;
int dp[N][N],sm[N][N];//when you're in pos i,lst 0 is in pos j
int main(){
    //freopen("aspect.out","w",stdout);
    //freopen("aspect.in","r",stdin);
    scanf("%d",&n);
    cin>>s;
    s=" "+s;
    dp[0][0]=1;
    sm[0][0]=1;
    for(int i = 1;i<=n;i++){
        if(s[i]=='1'){
            for(int j = 0;j<=i;j++){
                dp[i][j]=1ll*dp[i-1][j]*(i-j)%mod;
                sm[i][j]+=dp[i][j];
                if(j>0)sm[i][j]+=sm[i][j-1];
                sm[i][j]%=mod;
                
            }
        }else{
            for(int j = 1;j<=i;j++){
                dp[i][j]=sm[i-1][j-1];
                if(j!=1)dp[i][j]+=1ll*dp[i-1][j-1]*(j-1)%mod;
                dp[i][j]%=mod;
                sm[i][j]+=dp[i][j];
                sm[i][j]+=sm[i][j-1];
                sm[i][j]%=mod;
            }
        }
    }
    printf("%d\n",sm[n][n]);
}