#include<bits/stdc++.h>

using namespace std;

typedef long long llint;
typedef pair <int, int> pi;

const int MAXN = 6000005;
const int MOD = 998244353;

int n;
string s;
int a[MAXN];

int cnt, curr;
int ch[MAXN][10];
int len[MAXN], suf[MAXN], val[MAXN];
llint sum[MAXN];

void init () {
	cnt = 2; curr = 1;
	len[1] = -1; suf[1] = 1;
	len[2] = 0; suf[2] = 1;
}

void ubaci (int i, int c) {

	while (i - len[curr] - 1 < 0 || a[i - len[curr] - 1] != c) {
		curr = suf[curr];
	}
	
	if (ch[curr][c] != 0) {
		curr = ch[curr][c];
		val[curr]++;
		return;
	}
	cnt++;
	len[cnt] = len[curr] + 2;
	ch[curr][c] = cnt;
	int tmp = suf[curr];
	curr = cnt;
	val[curr]++;

	
	if (len[curr] == 1) {
		suf[curr] = 2;
		return;
	} else if (len[curr] == 2) {
		suf[curr] = ch[1][c];
		return;
	}
	
	while (i - len[tmp] - 1 < 0 || a[i - len[tmp] - 1] != c) {
		tmp = suf[tmp];
	}
	suf[curr] = ch[tmp][c];
}

llint aa[MAXN][2];

void eval (int gdje) {
	llint res = 0;
	for (int i = cnt; i >= 1; i--) {
		sum[i] = 0;
	}
	for (int i = cnt; i >= 1; i--) {
		sum[i] += val[i];
		sum[suf[i]] += sum[i];
		aa[i][gdje] = sum[i];
	}
}

int main () {
	init();
	cin >> n >> s;
	for (int i = 0; i < 2 * n; i++) {
		a[i] = s[i % n] - '0';
	}
	for (int i = 0; i < n; i++) {
		ubaci(i, a[i]);
	}
	eval(0);
	for (int i = 0; i < n; i++) {
		ubaci(i + n, a[i + n]);

	} 
	eval(1);
	llint sol = 0;
	for(int i = cnt;i >= 3;i--) {
		if(len[i] > n) continue;
		llint kol = aa[i][1] - aa[i][0];
		sol += kol * kol % MOD * len[i] % MOD;
		sol %= MOD;
	}
	cout << sol << endl;
	return 0;
}