#include<bits/stdc++.h> namespace { #pragma GCC diagnostic ignored "-Wunused-function" #include<atcoder/all> #pragma GCC diagnostic warning "-Wunused-function" using namespace std; using namespace atcoder; #define rep(i,n) for(int i = 0; i < (int)(n); i++) #define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--) #define all(x) begin(x), end(x) #define rall(x) rbegin(x), rend(x) template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; } template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; } using ll = long long; using P = pair<int,int>; using VI = vector<int>; using VVI = vector<VI>; using VL = vector<ll>; using VVL = vector<VL>; using mint = modint998244353; } int main() { ios::sync_with_stdio(false); cin.tie(0); int n; cin >> n; string s; cin >> s; mint ans; rep(k, n) { vector<mint> dp(n + 1); dp[n] = 1; dp[n - 1] = -1; for(int i = n; i > 0; i--) { dp[i - 1] += dp[i]; dp[i - 1] += dp[i]; if (i - 1 - k >= 0 && s[i - 1 - k] == '1') { dp[i - 1 - k] -= dp[i]; } } ans += (mint(2).pow(n - 1) - dp[0]) * mint(2).pow(k); } cout << ans.val() << '\n'; }