#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define op(x) ((x&1)?x+1:x-1)
#define odd(x) (x&1)
#define even(x) (!odd(x))
#define lc(x) (x<<1)
#define rc(x) (lc(x)|1)
#define lowbit(x) (x&-x)
#define mp(x,y) make_pair(x,y)
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
using namespace std;
const int MAXN = 6e6+10,mod = 998244353;

char s[MAXN];
int n,fail[MAXN],len[MAXN],ch[MAXN][10],cnt[MAXN],tot;

ll ans;

int main(){
	ios::sync_with_stdio(false);cin.tie(0);

	cin>>n>>(s+1);
	rep(i,1,n)s[n+i] = s[i];

	tot = 1;len[1] = -1;fail[0] = 1;

	s[0]='#';

	int u = 0;
	rep(i,1,2*n){
		int c = s[i]-'0';
		int tmp = u;
		while(s[i-1-len[tmp]] != s[i])tmp = fail[tmp];
		if(!ch[tmp][c]){
			len[++tot] = len[tmp]+2;
			int tmp2=fail[tmp];
			while(s[i-1-len[tmp2]] != s[i])tmp2 = fail[tmp2];
			fail[tot] = ch[tmp2][c];
			ch[tmp][c] = tot;
		}

		u = ch[tmp][c];
		
		if(i>n)cnt[u]++;
	}

	per(i,tot,2){
		cnt[fail[i]]+=cnt[i];
		assert(fail[i]<i);
	}

	rep(i,2,tot)if(len[i] <= n){
		ans += 1ll*cnt[i]*cnt[i]%mod*len[i];
		ans%=mod;
	}
	cout<<ans<<endl;

    return 0;
}