#include<bits/stdc++.h>
#define L(i, j, k) for(int i = (j); i <= (k); ++i)
#define R(i, j, k) for(int i = (j); i >= (k); --i)
#define ll long long
#define vi vector <int>
#define sz(a) ((int) (a).size())
#define me(f, x) memset(f, x, sizeof(f))
#define uint unsigned int
#define ull unsigned long long 
#define i128 __int128
using namespace std; 
const int N = 6e6 + 7, mod = 998244353;
int n, p, ch[N][10], f[N], len[N], dep[N];
char s[N]; 
int getfa(int x) {
	for(; p < len[x] + 1 || s[p - len[x] - 1] != s[p]; x = f[x]) ;
	return x;
}
int lst, tot = 1; 
void ins() {
	lst = getfa(lst);
	if(!ch[lst][s[p] - '0']) 
		++tot, f[tot] = ch[getfa(f[lst])][s[p] - '0'], 
		ch[lst][s[p] - '0'] = tot, dep[tot] = dep[f[tot]] + 1, len[tot] = len[lst] + 2;
	lst = ch[lst][s[p] - '0'];
}

string S;
int fan[N];
int main() {
//	freopen("data.txt", "r", stdin);
	ios :: sync_with_stdio(false);
	cin.tie(0); cout.tie(0);
	f[0] = 1, len[1] = -1;
	cin >> n;
	cin >> S;
	L(i, 0, n - 1) 
		s[i + 1] = s[i + n + 1] = S[i];
	L(i, 1, n * 2) {
		p = i, ins();
		if(i > n) {
			fan[lst] += 1;
		}
	}
	
	R(i, tot, 1) {
		fan[f[i]] += fan[i];
	}
	const int mod =998244353;
	ll ans = 0;
	L(i, 1, tot) if(1 <= len[i] && len[i] <= n) {
		(ans += (ll) len[i] * fan[i] % mod * fan[i] % mod) %= mod;
	}
	cout << ans << '\n';
	return 0;
}