#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define mk make_pair
#define lowbit(x) (x&(-x))
#define pb emplace_back
#define pr pair<int,int>
#define let const auto
const int N=6e6+5,mod=998244353;
int read(){
	int x=0,f=1; char c=getchar();
	while(('0'>c||c>'9')&&c!='-') c=getchar();
	if(c=='-') f=0,c=getchar();
	while('0'<=c&&c<='9') x=(x<<1)+(x<<3)+(c^48),c=getchar();
	return f?x:-x;
}
char s[N];
int n,lst;
struct PAM{
	char s[N];
	int trie[N][10],len[N],fail[N],cur,tot,cnt;
	ll num[N];
	void init(){fail[0]=1; len[1]=-1; tot=1;}
	int getfail(int st,int i){
		while(i-len[st]<2||s[i-len[st]-1]!=s[i]) st=fail[st];
		return st;
	}
	void insert(const char c,int i){
		int p=c-'0';
		s[++cnt]=c;
		int nxt=getfail(cur,cnt);
		if(!trie[nxt][p]){
			fail[++tot]=trie[getfail(fail[nxt],cnt)][p];
			trie[nxt][p]=tot;
			len[tot]=len[nxt]+2;
		}
		cur=trie[nxt][p];
		if(i>n) num[cur]++;
	}
	ll getMax(){
		ll ans=0;
		for(int i=tot; i; i--) ans+=1ll*num[i]*num[i]%mod*(len[i]<=n?len[i]:0)%mod,num[fail[i]]+=num[i];
		return ans%mod;
	}
}S;

int main(){
	n=read();
	scanf("%s",s+1);
	S.init();
	for(int i=1; i<=n; i++)
		S.insert(s[i],i);
	for(int i=1; i<=n; i++) S.insert(s[i],i+n);
	cout<<S.getMax()<<'\n';
	return 0;
}