#include<bits/stdc++.h>
using namespace std;
constexpr int M=6e6+5,mod=998244353;
char s[M];int n,ans;
namespace pam{ char str[M];
	int num,tot,last,cnt[M],tmp[M],len[M],fail[M],tr[M][10];
	void init(){fail[0]=1;len[1]=-1;num=1;str[0]='@';}
	int getfail(int x){while (str[tot-len[x]-1]!=str[tot]) x=fail[x];return x;}
	int new_node(int l){return len[++num]=l,num;}
	void insert(char ch){
		str[++tot]=ch;
		int now=getfail(last);
		if (!tr[now][ch-'0']){
			int x=new_node(len[now]+2);
			fail[x]=tr[getfail(fail[now])][ch-'0'];
			tr[now][ch-'0']=x;
		}
		cnt[last=tr[now][ch-'0']]++;
	}
	void solve(int op){for (int i=1;i<=num;i++) tmp[i]+=op*cnt[i];}
	void calc(){
		for (int i=num;i;i--) tmp[fail[i]]+=tmp[i];
		for (int i=2;i<=num;i++) if (len[i]<=n)
			ans=(ans+1ll*tmp[i]*tmp[i]%mod*len[i])%mod;
	}
};
int main(){
	pam::init();
	scanf("%d%s",&n,s);
	for (int i=0;i<n;i++) pam::insert(s[i]);
	pam::solve(-1);
	for (int i=0;i<n;i++) pam::insert(s[i]);
	pam::solve(1);
	pam::calc();
	if (ans<0) ans+=mod;
	printf("%d\n",ans);
	return 0;
}