#include<bits/stdc++.h>
using namespace std;
#define int long long
const int mod = 998244353;
signed main(){
	int n;
	cin >> n;
	string s;
	cin >> s;
	vector<int> a;
	for(int i = 0;i < n;i++) if(s[i] == '1') a.push_back(i);
	if((int)a.size() == 0) cout << 0;
	else if((int)a.size() == 1) cout << 1;
	else{
	  int ans = 1;
	  for(int j = 0;j < (int)a.size() - 1;j++){
	    ans *= (a[j + 1] - a[j] + 1);
	    ans %= mod;
	  }
	  cout << ans % mod << endl;
	}
  
}