#include<bits/stdc++.h>
#define ios ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define all(x)	x.begin(),x.end()
#define endl '\n'
//#define int long long
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
const int mod = 998244353;
const int N = 1e5 + 5;

struct PAM {
	static const int maxn = 6e6 + 5;;
	int S[maxn];
	int nxt[maxn][10];
	int fail[maxn], cnt[maxn], num[maxn], len[maxn];
	int last, n, p;
	int newnode(int l) {
		for (int i = 0; i < 26; ++i) nxt[p][i] = 0;
		cnt[p] = 0;	num[p] = 0;	len[p] = l;
		return p++;
	}
	PAM() { clear(); }
	void clear() {
		p = 0;	newnode(0);	newnode(-1);
		last = 0;	n = 0;
		S[n] = -1;	fail[0] = 1;
	}
	int get_fail(int x) {
		while (S[n - len[x] - 1] != S[n]) x = fail[x];
		return x;
	}
	void insert(int c) {
		c -= '0';	S[++n] = c;
		int cur = get_fail(last);
		if (!nxt[cur][c]) {
			int now = newnode(len[cur] + 2);
			fail[now] = nxt[get_fail(fail[cur])][c];
			nxt[cur][c] = now;
			num[now] = num[fail[now]] + 1;
		}
		last = nxt[cur][c];
		//cnt[last]++;
	}
	void count() {
		for (int i = p - 1; i >= 0; --i) {
			if (fail[i] >= 2)	cnt[fail[i]] += cnt[i];
		}
	}
	//ll solve() {//P3649
	//	count();
	//	ll res = 0;
	//	for (int i = 2; i <= p - 1; ++i)	res = max(res, 1ll * cnt[i] * len[i]);
	//	return res;
	//}x
	ll solve() {
		count();
		ll res = 0;
		for (int i = 2; i <= p - 1; ++i) {
			if (len[i] <= n / 2) {
				//cout << "-->" << cnt[i] << ' ' << len[i] << endl;
				(res += 1ll * cnt[i] * cnt[i] % mod * len[i] % mod) %= mod;
			}
		}
		return res;
	}
};
PAM pam;
//n<=3e6, ∑={0-9}
//对所有不同的回文子串求 ∑cnt^2*len
//回文子串：s[i-j] 或 s[i-n] + s[1,j]
void AC() {
	int n;	cin >> n;
	string s;	cin >> s;
	s = ' ' + s;
	for (int i = 1; i <= 2 * n; ++i) {
		if (i <= n)	pam.insert(s[i]);
		else {
			pam.insert(s[i - n]);
			++pam.cnt[pam.last];
		}
	}
	cout << pam.solve() << endl;
}
signed main() {
	ios;
	int o_o = 1;
	//cin >> o_o;
	while (o_o--)  AC();
	return 0;
}
/*
01010
*/