//Author: Kevin
#include<bits/stdc++.h>
//#pragma GCC optimize("O2")
using namespace std;
#define ll long long
#define ull unsigned ll
#define pb emplace_back
#define mp make_pair
#define ALL(x) (x).begin(),(x).end()
#define rALL(x) (x).rbegin(),(x).rend()
#define srt(x) sort(ALL(x))
#define rev(x) reverse(ALL(x))
#define rsrt(x) sort(rALL(x))
#define sz(x) (int)(x.size())
#define inf 0x3f3f3f3f
#define pii pair<int,int>
#define lb(v,x) (int)(lower_bound(ALL(v),x)-v.begin())
#define ub(v,x) (int)(upper_bound(ALL(v),x)-v.begin())
#define uni(v) v.resize(unique(ALL(v))-v.begin())
#define longer __int128_t
void die(string S){puts(S.c_str());exit(0);}
class PalindromeAutomaton
{
	public:
		struct node
		{
			int len,fail;
			int cnt;
			int trans[12];
			int num;
			node(int _len=-1,int _fail=0,int _num=0)
			{
				num=_num;
				len=_len;
				fail=_fail;
				cnt=0;
				memset(trans,0,sizeof(trans));
			}
		}Node[6001000];
		vector<int> G[6001000];
		int tot,last;
		void clear()
		{
			Node[0]=node(0,1,0);
			Node[1]=node(-1,0,0);
			tot=2;
			last=0;
		}
		PalindromeAutomaton()
		{
			clear();
		}
		ll ans;
		void dfs(int x,int lim)
		{
			for(auto y:G[x])
			{
//				cerr<<x<<" -> "<<y<<endl;
				dfs(y,lim);
				Node[x].cnt+=Node[y].cnt;
			}
			if(Node[x].len<=lim&&Node[x].len>0)
			{
				ans=(ans+1ll*Node[x].cnt*Node[x].cnt%998244353*Node[x].len)%998244353;
//				cerr<<x<<" "<<Node[x].cnt<<" "<<Node[x].len<<endl;
			}
//			else
//				cerr<<". "<<x<<" "<<Node[x].cnt<<" "<<Node[x].len<<endl;
		}
		void solve(int lim)
		{
			for(int i=0;i<=tot;i++) if(i!=1)
				if(Node[i].fail>=0)
					G[Node[i].fail].pb(i);
			ans=0;
			dfs(1,lim);
			cout<<ans<<endl;
		}
		void extend(string s)
		{
			clear();
			int n=sz(s);
			s='!'+s;
			for(int i=1;i<=n;i++)
			{
				int x=s[i]-'0';
//				cout<<"# "<<x<<" ";
				while(s[i-Node[last].len-1]!=s[i]) last=Node[last].fail;
//				cout<<"$ "<<last<<endl;
				if(Node[last].trans[x])
				{
					if(i>(n/2))
						Node[Node[last].trans[x]].cnt++;
					last=Node[last].trans[x];
				}
				else
				{
					tot++;
					int v=Node[last].fail;
//					cout<<v<<endl;
					while(s[i-Node[v].len-1]!=s[i]) v=Node[v].fail;
					Node[tot]=node(Node[last].len+2,Node[v].trans[x],Node[Node[v].trans[x]].num+1);
					if(i>(n/2))
						Node[tot].cnt++;
					Node[last].trans[x]=tot;
					last=Node[last].trans[x];
				}
//				cout<<"! "<<last<<endl;
//				cout<<"& "<<Node[last].len<<endl;
//				cerr<<Node[last].cnt<<" "<<Node[last].fail<<endl;
			}
			solve(n/2);
		}
}pam;
int main()
{
	int n;
	cin>>n;
	string s;
	cin>>s;
	pam.extend(s+s);
	return 0;
}