#include<bits/stdc++.h>

using namespace std;

const int N = 2005, mod = 998244353;

int n, d[N], dp[N][N];
char c;

int main(){
  cin >> n;
  dp[0][n] = 1;
  for(int i = 1; i <= n; ++i){
    cin >> c;
    for(int j = 0; j <= n; ++j){
      d[j] = 0;
    }
    for(int j = 0; j <= n; ++j){
      if(c == '1'){
        if(j){
          dp[i][j - 1] = (dp[i][j - 1] + 1ll * dp[i - 1][j] * j % mod) % mod;
        }
      }
      else{
        dp[i][j] = (dp[i][j] + 1ll * dp[i - 1][j] * max(0, n - i + 1 - j) % mod) % mod;
        d[0] = (d[0] + dp[i - 1][j]) % mod;
        d[j] = (d[j] + mod - dp[i - 1][j]) % mod;
      }
    }
    for(int j = 0; j <= n; ++j){
      d[j] = ((j ? d[j - 1] : 0) + d[j]) % mod;
      dp[i][j] = (dp[i][j] + d[j]) % mod;
    }
  }
  cout << dp[n][0];
  return 0;
}