#include <bits/stdc++.h>

using namespace std;
using i64 = long long;

constexpr i64 p = 998244353;

struct PAM {
    const static int S = 10;
    struct Node {
        int len, link;
        int cnt {};
        array<int, S> nxt {};
    };
    int last;
    string s;
    vector<Node> t;
    int newNode(int len, int link) {
        t.emplace_back();
        t.back() = {len, link};
        return (int)t.size() - 1;
    }
    PAM() : last(1), s(1, ' ') {
        newNode(0, 1);
        newNode(-1, 1);
    }
    int jump(int u) { // p指向要匹配的字符的位置, u为初始开始匹配节点位置
        int p = (int)s.size() - 1;
        while (s[p - t[u].len - 1] != s[p]) {
            u = t[u].link;
        }
        return u;
    }
    int insert(char ch) {
        s.push_back(ch);
        int u = jump(last);
        int v = t[u].nxt[ch - '0'];
        if (!v) {
            int link = t[jump(t[u].link)].nxt[ch - '0'];
            v = t[u].nxt[ch - '0'] = newNode(t[u].len + 2, link);
        }
        last = v;
        t[v].cnt++;
        return last;
    }
};

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);

    int n;
    cin >> n;
    string s;
    cin >> s;
    s += s;
    s.insert(0, " ");

    PAM pam;
    for (int i = 1; i <= n; i++) {
        pam.insert(s[i]);
    }

    auto nodes = pam.t;
    vector<i64> temp(nodes.size());
    for (int i = (int)nodes.size() - 1; i >= 2; i--) {
        temp[i] += nodes[i].cnt;
        temp[i] %= ::p;
        temp[nodes[i].link] += temp[i];
        temp[nodes[i].link] %= ::p;
    }
    
    for (int i = n + 1; i <= 2 * n; i++) {
        pam.insert(s[i]);
    }
    vector<i64> cnt(pam.t.size());
    for (int i = (int)pam.t.size() - 1; i >= 2; i--) {
        cnt[i] += pam.t[i].cnt;
        cnt[pam.t[i].link] += cnt[i];
        cnt[i] %= ::p;
        cnt[pam.t[i].link] %= ::p;
    }

    i64 ans = 0;
    for (int i = 2; i < (int)cnt.size(); i++) {
        if (pam.t[i].len > n) continue;
        if (i < (int)temp.size()) {
            cnt[i] -= temp[i];
            cnt[i] = (cnt[i] + ::p) % ::p;
        }
        ans += cnt[i] * cnt[i] % ::p * pam.t[i].len;
        ans %= ::p;
    }

    cout << ans << "\n";



    return 0;
}