#include<bits/stdc++.h> using namespace std; const int N=2010,MOD=998244353; int n,f[N][N],sum[N][N]; char s[N]; int ans; signed main(){ //freopen("test.in","r",stdin); scanf("%d",&n); scanf("%s",s+1); f[0][0]=1; sum[0][0]=1; for(int i=0;i<n;i++){ sum[i][0]=f[i][0]; for(int j=1;j<=n;j++){ sum[i][j]=sum[i][j-1]+f[i][j]; } if(s[i+1]=='0'){ for(int j=1;j<=i+1;j++){ f[i+1][j]+=sum[i][j-1]; } for(int j=0;j<=i;j++){ f[i+1][j+1]+=f[i][j]*j; } }else{ for(int j=0;j<=i;j++){ f[i+1][j]=f[i][j]*(i-j+1); } } } for(int i=1;i<=n;i++){ ans+=f[n][i]; ans%=MOD; } printf("%d\n",ans); return 0; } //f[i][j]:process the permutation until i, j is //the biggest 0 element //s[i+1]==0: p[i+1]>j: f[i+1][j+1]=sigma(f[i][k]); j<k<n // p[i+1]<j: f[i+1][j+1]=f[i][j]*j // f[i+1][j+1]=sigma(f[i][k])+f[i][j]*j; //s[i+1]==1: f[i+1][j]=f[i][j]*(i-j+1)