#include <bits/stdc++.h>

template<int MAXN = 4500000, int MAXC = 10>
struct palindromic_tree {
	struct node {
		node *child[MAXC], *fail; int len;
		node(int len = 0) : fail(NULL), len(len) {
			memset(child, NULL, sizeof(child)); }
	} node_pool[MAXN * 2], *tot_node;
	int size, text[MAXN * 2];
	node *odd, *even, *last;
	node *match(node *now) {
		for (; text[size - now -> len - 1] != text[size]; now = now -> fail);
		return now; }
	bool extend(int token) {
		text[++size] = token; node *now = match(last);
		if (now -> child[token])
			return last = now -> child[token], false;
		if (tot_node == node_pool + MAXN * 2) while (true);
		last = now -> child[token] = new (tot_node++) node(now -> len + 2);
		if (now == odd) last -> fail = even;
		else {
			now = match(now -> fail);
			last -> fail = now -> child[token]; }
		return true; }
	void init() {
		text[size = 0] = -1; tot_node = node_pool;
		last = even = new(tot_node++) node(0); odd = new(tot_node++) node(-1);
		even -> fail = odd; }
	palindromic_tree() { init(); } };

const int MOD = 998244353;
const int MAXN = 4500000;

palindromic_tree<> _p;
int N;
char str[3000001];
int sum1[MAXN * 2], sum2[MAXN * 2];

int main() {
	scanf("%d", &N);
	scanf(" %s", str);
	for (int i = 0; i < N; ++i) {
		_p.extend(str[i] - '0');
		++sum1[_p.last - _p.node_pool];
		++sum2[_p.last - _p.node_pool];
	}
	for (int i = _p.tot_node - _p.node_pool - 1; i >= 0; --i) {
		if (_p.node_pool[i].fail)
			sum1[_p.node_pool[i].fail - _p.node_pool] += sum1[i];
	}
	for (int i = 0; i < N; ++i) {
		_p.extend(str[i] - '0');
		++sum2[_p.last - _p.node_pool];
	}
	int ans2 = 0;
	for (int i = _p.tot_node - _p.node_pool - 1; i >= 0; --i) {
		if (_p.node_pool[i].fail)
			sum2[_p.node_pool[i].fail - _p.node_pool] += sum2[i];
		int f = _p.node_pool[i].len;
		if (f > 0 && f <= N) {
			ans2 = (ans2 + 1ll * (sum2[i] - sum1[i]) * (sum2[i] - sum1[i]) % MOD * f) % MOD;
		}
	}
	printf("%d\n", ans2);
}