#include<bits/stdc++.h>
using namespace std;
const int mod = 998244353;
using vi = vector<int>;
#define sz(x) int(x.size())
#define rep(i, a, b) for(int i = (a); i < (b); i++)
struct Node {
    int jump, len;
    array<int, 10> to;
    Node() {
        to.fill(0);
    }
};
vector<Node> tree;
void build(string s) {
    auto get_link = [&](int cur, int pos) {
        while(pos - 1 - tree[cur].len < 0 || s[pos - 1 - tree[cur].len] != s[pos])
            cur = tree[cur].jump;
        return cur;
    };

    vector<int> sub(sz(s) + 2);
    tree.resize(sz(s) + 2);
    tree[0].len = -1;
    tree[1].jump = 0;
    int cur = 0, sz = 2;
    rep(i, 0, sz(s)) {
        int par = get_link(cur, i);
        if(tree[par].to[s[i] - '0'] == 0) {
            tree[sz].len = tree[par].len + 2;
            tree[sz].jump = max(1, tree[get_link(tree[par].jump, i)].to[s[i] - '0']);
            // g[tree[sz].jump].push_back(sz);
            tree[par].to[s[i] - '0'] = sz++;
        }
        cur = tree[par].to[s[i] - '0'];
        if(i >= s.size() / 2)
            sub[cur]++;
        // cout << i << " " << cur << " " << par << endl;
    }

    int ans = 0;
    for(int v = sz; v--;) {
        sub[tree[v].jump] += sub[v];
        if(tree[v].len > 0 && tree[v].len <= s.size() / 2) {
            // cout << v << " (" << tree[v].len << " " << sub[v] << endl;
            ans = (ans + tree[v].len * 1ll * (sub[v] * 1ll * sub[v] % mod)) % mod;
        }
    }
    cout << ans << endl;
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    int n;
    string s(1e6, 'a');
    cin >> n >> s;

    build(s + s);
}