#include<bits/stdc++.h>
using namespace std;
const int N = 1.2e7+7;
int Next[N],len[N];
int tr[N][10],occ[N];
int n,m;
int pos[N];
int tot=1;
char s[N];
int getNext(int x,int i)
{
	while(i-len[x]-1<0||s[i-len[x]-1]!=s[i]) x=Next[x];
	return x;
}
int cur=0;
const int mod = 998244353;
int main()
{
    cin>>n;
	scanf("%s",s+1);
	for(int i=1;i<=n;i++)s[i+n]=s[i];
	reverse(s+1,s+2*n+1);
	Next[0]=1;len[1]=-1;
	int last=0;
	for(int i=1;i<=2*n;i++)
	{
		int c=s[i]-'0';
		int p=getNext(cur,i);
		if(!tr[p][c])
		{
			int q=++tot;
			Next[q]=tr[getNext(Next[p],i)][c];
			tr[p][c]=q;
			len[q]=len[p]+2;
		}
		cur=tr[p][c];
		if(i>n)occ[cur]++;
	}
	int ans=0;
	for(int i=tot;i>=2;i--)
    {
        occ[Next[i]]+=occ[i];
        if(len[i]<=n)ans+=1ll*occ[i]*occ[i]%mod*len[i]%mod,ans%=mod;
    }
    cout<<ans;
	return 0;
}