#include <bits/stdc++.h>
using namespace std;

using ll = long long;
#define int ll

#define endl '\n'
#define pb push_back
using pi = pair<int, int>;

const int MOD = 998244353;

int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  
  int n;
  string s;
  cin >> n >> s;
  s = '$' + s;
  
  vector<int> dp(n + 1);
  dp[0] = 1;
  int last = 0;
  for (int i = 1; i <= n; ++i) {
    if (s[i] == '1') last = i;
    dp[i] = dp[i - 1];
    if (last) dp[i] = (dp[i] + dp[last - 1]) % MOD;
  }
  
  cout << (dp[n] - dp[n - 1] + MOD) % MOD;
}