#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<vector>
#define LL long long
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define mod 998244353
using namespace std;
inline int read(){
    int f=1,ans=0; char c=getchar();
    while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
    while(c>='0'&&c<='9'){ans=ans*10+c-'0';c=getchar();}
    return f*ans;
}
const int MAXN = 6e6 + 11;
int ch[MAXN][10], cnt, tot, fail[MAXN], lst, len[MAXN], siz[MAXN];
int node(int l){cnt++; len[cnt] = l; return cnt;}
char str[MAXN];
vector<int> vec[MAXN];
void Init(){
	cnt = -1; str[0] = '&'; 
	node(0), node(-1); fail[0] = 1;
	lst = 0;
}
int getfail(int x, char c){
	while(str[tot - len[x] - 1] != c){
		x = fail[x];
	}
	return x;
}
int N;
int ret;
void ins(char c, int id){
	tot++; int now = getfail(lst, c);
	if(!ch[now][c - '0']){
		int x = node(len[now] + 2);
		fail[x] = ch[getfail(fail[now], c)][c - '0'];
		ch[now][c - '0'] = x;
	}lst = ch[now][c - '0']; 
	if(id > N) siz[lst]++;
}
void dfs(int u){
	for(auto v: vec[u]) dfs(v), siz[u] += siz[v];
	if(len[u] <= N && len[u] >= 1) ret += 1ll * siz[u] * siz[u] % mod * len[u] % mod, ret %= mod;
	return;
}
signed main(){
	N = read(); Init();
	scanf("%s", str + 1); for(int i = N + 1; i <= 2 * N; i++) str[i] = str[i - N];
	for(int i = 1; i <= 2 * N; i++) ins(str[i], i);
	for(int i = 0; i <= cnt; i++) if(i != 1) vec[fail[i]].pb(i);
	dfs(1);
	printf("%d\n", ret);
}