#include <bits/stdc++.h>
using namespace std;
const int maxn = 6e6 + 5;
int n;
int val[maxn], par[maxn], go[maxn][10], lst, cnt, tot[maxn];
string s;
const int mod = 998244353;
void extend(int x)
{
    int p = lst, c = s[x] - '0';
    while (s[x - val[p] - 1] != s[x])
        p = par[p];
    if (!go[p][c]) {
        int q = ++cnt, now = p;
        val[q] = val[p] + 2;
        do {
            p = par[p];
        } while (s[x - val[p] - 1] != s[x]);
        par[q] = go[p][c];
        lst = go[now][c] = q;
    } else
        lst = go[p][c];
    if (x > n)
        tot[lst]++;
}
int main()
{
    par[0] = cnt = 1;
    val[1] = -1;
    cin >> n;
    cin >> s;
    s = ' ' + s + s;
    for (int i = 1; i <= 2 * n; ++i) {
        extend(i);
    }
    long long ans = 0;
    for (int i = cnt; i >= 0; i--) {
        tot[par[i]] += tot[i];
    }
    for (int i = 1; i <= cnt; i++) {
        if(val[i]<=n&&val[i]>=1)ans = (ans + 1ll * val[i] * tot[i]%mod*tot[i] % mod) % mod;
        //cout << val[i] << " " << tot[i] << endl;
    }
    cout << ans << endl;
}