#include <bits/stdc++.h>
#define int long long
using namespace std;
#define YES "YES"
#define NO "NO"
#define all(a) a.begin(), a.end()
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
const double eps = 1e-9;
const int N = 3e6 + 100;
const int M = 1e6 + 5e5 + 100;
const int INF = 1e16 + 100;
const int mod = 998244353;
const int base = 23333;
mt19937 rng(std::chrono::steady_clock::now().time_since_epoch().count());
int n, cnt, ans, flag = 1;
string s;
int d[N + N / 2];
int nxt[M][24];
int lef[N + N / 2];
struct node
{
    int son[10], num = 0, add = 0, h = 0, fa = 0, deg = 0;
} trie[M];
void topu()
{
    queue<int> q;
    for (int i = 0; i <= cnt; i++)
    {
        if (trie[i].deg == 0)
            q.push(i);
    }
    while (!q.empty())
    {
        int u = q.front();
        q.pop();
        int v = trie[u].fa;
        trie[v].add = (trie[v].add + trie[u].add) % mod;
        trie[v].deg--;

        if (trie[v].deg == 0)
            q.push(v);
        trie[u].num = (trie[u].num + trie[u].add) % mod;
        if (flag)
            ans = (ans + trie[u].num * trie[u].num % mod * (max(0ll, 2 * trie[u].h - 1)) % mod) % mod;
        else
            ans = (ans + trie[u].num * trie[u].num % mod * (2 * trie[u].h) % mod) % mod;
    }
}
void clear()
{
    for (int i = 0; i <= cnt; i++)
    {
        for (int j = 0; j < 10; j++)
        {
            trie[i].son[j] = 0;
        }
        trie[i].add = trie[i].deg = trie[i].fa = trie[i].h = trie[i].num = 0;
    }
}
int get(int u, int k)
{
    int i = 0;
    while (k)
    {
        if (k & 1)
            u = nxt[u][i];
        k = k >> 1;
        i++;
    }
    return u;
}
void solve()
{
    cin >> n;
    cin >> s;
    s = s + s;
    // 奇数
    // n = 100000;
    // s = "";

    // for (int i = 1; i <= 150000; i++)
    // {
    //     s += '2';
    // }
    // cout << s << '\n';
    // printf("YES\n");
    for (int i = 0, l = 0, r = -1; i < n + n / 2; i++)
    {
        int k = 0, pos = 0;
        if (i <= r)
        {
            k = min(d[l + r - i], r - i + 1);
            pos = lef[l + r - i];
            if (d[l + r - i] > r - i + 1)
                pos = get(pos, trie[pos].h - (r - i + 1));
        }
        if (pos)
            trie[pos].add++;
        while (0 <= i - k && i + k < 2 * n && k < (n + 1) / 2 && s[i - k] == s[i + k])
        {
            int v = s[i + k] - '0';
            if (!trie[pos].son[v])
            {
                trie[pos].son[v] = ++cnt;
                trie[pos].deg++;
            }
            int x = trie[pos].son[v];

            trie[x].fa = pos;
            trie[x].num++;
            trie[x].h = trie[pos].h + 1;

            // update

            nxt[x][0] = pos;
            for (int j = 1; j < 24; j++)
            {
                if ((1 << j) > trie[x].h)
                    break;
                nxt[x][j] = nxt[nxt[x][j - 1]][j - 1];
            }

            pos = trie[pos].son[v];
            k++;
        }
        d[i] = k--;
        lef[i] = pos;
        if (i + k > r)
        {
            l = i - k;
            r = i + k;
        }
    }
    for (int i = 0; i < n / 2; i++)
    {
        trie[lef[i]].add = (trie[lef[i]].add + mod - 1) % mod;
    }
    // printf("YES\n");
    topu();
    clear();
    flag = 0;
    // printf("YES\n");
    // 偶数
    cnt = 0;
    for (int i = 0, l = 0, r = -1; i < n + n / 2; i++)
    {
        int k = 0, pos = 0;
        if (i <= r)
        {
            k = min(d[l + r - i + 1], r - i + 1);
            pos = lef[l + r - i + 1];
            if (d[l + r - i + 1] > r - i + 1)
                pos = get(pos, trie[pos].h - (r - i + 1));
        }
        if (pos)
            trie[pos].add++;
        while (0 <= i - k - 1 && i + k < 2 * n && k < n / 2 && s[i - k - 1] == s[i + k])
        {
            int v = s[i + k] - '0';
            if (!trie[pos].son[v])
            {
                trie[pos].son[v] = ++cnt;
                trie[pos].deg++;
            }
            int x = trie[pos].son[v];
            trie[x].fa = pos;
            trie[x].num++;
            trie[x].h = trie[pos].h + 1;

            // update

            nxt[x][0] = pos;
            for (int j = 1; j < 24; j++)
            {
                if ((1 << j) > trie[x].h)
                    break;
                nxt[x][j] = nxt[nxt[x][j - 1]][j - 1];
            }

            pos = trie[pos].son[v];
            k++;
        }
        d[i] = k--;
        lef[i] = pos;
        if (i + k > r)
        {
            l = i - k - 1;
            r = i + k;
        }
    }
    for (int i = 0; i < n / 2; i++)
    {
        trie[lef[i]].add = (trie[lef[i]].add + mod - 1) % mod;
    }
    topu();
    cout << ans << '\n';
    // printf("%lld\n", ans);
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
    // cin >> t;
    while (t--)
        solve();
    return 0;
}