#include <bits/stdc++.h>
#include <fstream>

using namespace std;

#define ll long long int
#define ld long double
#define F first
#define S second
#define MOD 998244353

void solve(){
	ll n;
	cin >> n;
	string s;
	cin >> s;
	ll cnt=0;
	bool first = true;
	ll add = 0;
	for	(ll i=0;i<n;i++){
		while(i<n && s[i] != '1'){
			i++;
			add++;
		}
		if(i >= n){
			break;
		}
		if(first){
			cnt = 1;
			first = false;
		}else{
			ll tmp = (cnt*add)%MOD;
			cnt = (cnt*2)%MOD;
			cnt += tmp;
		}
		add = 0;
		if(cnt > MOD){
			cnt -= MOD;
		}
	}
	cout << cnt;
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	ll t=1;
	while(t--){
		solve();
	}
}