#include<bits/stdc++.h>

using namespace std;

const int N = 2e3 + 5;
const int mod = 998244353;

int n;
string a;
long long s[N][N], dp[N][N];

int main(){
  cin >> n >> a;
  a = ' ' + a;
  dp[0][n] = 1;
  for(int j = 0; j <= n; j++) s[0][j] = 1;
  for(int i = 1; i <= n; i++){
    for(int j = 0; j <= n; j++){
      if(a[i] == '0'){
        dp[i][j] = s[i - 1][j];
      }
      else{
        dp[i][j] = dp[i - 1][j + 1];
      }
    }
    for(int j = n; j >= 0; j--){
      s[i][j] = s[i][j + 1] + dp[i][j];
      while(s[i][j] >= mod) s[i][j] -= mod;
    }
  }
  cout << (dp[n][0] + dp[n][1]) % mod;
  return 0;
}