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

#define rep(i, a, n) for(int i=(a); i<(n); ++i)
#define per(i, a, n) for(int i=(a); i>(n); --i)
#define pb emplace_back
#define mp make_pair
#define clr(a, b) memset(a, b, sizeof(a))
#define all(x) (x).begin(),(x).end()
#define lowbit(x) (x & -x)
#define fi first
#define se second
#define lson o<<1
#define rson o<<1|1
#define gmid l[o]+r[o]>>1
 
using ll = long long;
using ull = unsigned long long;
using pii = pair<int,int>;
using pll = pair<ll, ll>;
using ui = unsigned int;
 
constexpr int mod = 998244353;
constexpr int inf = 0x3f3f3f3f;
constexpr double EPS = 1e-8;
const double PI = acos(-1.0);

constexpr int N = 4010;

int n;
string s;
ll f[N], dp[N], sum[N];

void _main(){
  cin >> n >> s;
  f[0] = 1;
  rep(i, 1, n + 1)  f[i] = (f[i-1] << 1) % mod;
  ll ans = 0;
  rep(i, 0, n){
    ll diff = 0;
    rep(j, 0, i){
      dp[j] = f[j];
      sum[j] = dp[j];
      if(j) sum[j] = (sum[j] + sum[j-1]) % mod;
      diff = (diff + dp[j]) % mod;
    }
    rep(j, i, n){
      if(j - i - 1 >= 0)  diff = (diff + mod - dp[j - i - 1]) % mod;
      if(s[j - i] == '0'){
        dp[j] = 1;
        if(j - i > 0) dp[j] = (dp[j] + sum[j - i - 1]) % mod;
        dp[j] = (dp[j] + diff) % mod;
      } else {
        dp[j] = diff;
        ll cur = 1;
        if(j - i > 0) cur = (cur + sum[j - i - 1]) % mod;
        cur = cur * f[i] % mod;
        if(n - j - 2 >= 0)  cur = cur * f[n - j - 2] % mod;
        ans += cur;
      }
      sum[j] = dp[j];
      if(j) sum[j] = (sum[j-1] + sum[j]) % mod;
      diff = (diff + dp[j]) % mod;
    }
  }
  cout << ans % mod << '\n';
}

int main(){
  ios::sync_with_stdio(0);
  cin.tie(0); cout.tie(0);
  _main();
  return 0;
}