#include <bits/stdc++.h>
using namespace std;
const int maxn = 6e6 + 5;
const int mod = 998244353;

int n, a[maxn];
namespace pam
{
    int sz, tot, last;
    int cnt[maxn], ch[maxn][10], len[maxn], fail[maxn], pos[maxn];
    char s[maxn];

    int node(int l)
    { // 建立一个新节点，长度为 l
        sz++;
        memset(ch[sz], 0, sizeof(ch[sz]));
        len[sz] = l;
        fail[sz] = cnt[sz] = 0;
        return sz;
    }

    void clear()
    { // 初始化
        sz = -1;
        last = 0;
        s[tot = 0] = '$';
        node(0);
        node(-1);
        fail[0] = 1;
    }

    int getfail(int x)
    { // 找后缀回文
        while (s[tot - len[x] - 1] != s[tot])
            x = fail[x];
        return x;
    }

    void insert(char c)
    { // 建树
        s[++tot] = c;
        int now = getfail(last);
        if (!ch[now][c - '0'])
        {
            int x = node(len[now] + 2);
            fail[x] = ch[getfail(fail[now])][c - '0'];
            ch[now][c - '0'] = x;
        }
        last = ch[now][c - '0'];
        cnt[last]++;
    }
    void solve()
    {
        for (int i = sz; i >= 0; i--)
            cnt[fail[i]] += cnt[i];
    }
} // namespace pam

char s[maxn];

int main()
{
    pam::clear();
    scanf("%d", &n);
    scanf("%s", s + 1);
    for (int i = n + 1; i <= n * 2; i++)
        s[i] = s[i - n];
    for (int i = 1; i <= n; i++)
        pam::insert(s[i]);
    pam::solve();
    memcpy(a, pam::cnt, sizeof(a));
    pam::clear();
    for (int i = 1; i <= n * 2; i++)
        pam::insert(s[i]);
    pam::solve();
    for (int i = 1; i <= pam::sz; i++)
        pam::cnt[i] -= a[i];
    int ans = 0;
    for (int i = 1; i <= pam::sz; i++)
    {
        if (pam::len[i] >= 1 && pam::len[i] <= n)
            ans = (ans + 1ll * pam::cnt[i] * pam::cnt[i] % mod * pam::len[i] % mod) % mod;
    }
    printf("%lld\n", ans);
    return 0;
}