#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define modd(a,b) a=a%b
#define pb push_back
#define db double
#define lowbit(x) x&(-x)
#define cerr(x) cout<<#x<<"="<<x<<endl
const ll mod=998244353;
ll ksm(ll a,ll b) {ll ans=1,bs=a;while(b) {if(b&1) ans=ans*bs%mod;bs=bs*bs%mod;b>>=1;}return ans;}
#define fi first
#define se second
#define N 3000010<<1
int n;
string s;
int t[N][10];
ll ans=0;
int cur=0,pos=0,tot=1;
int fail[N],len[N];
ll num[N];
int getfail(int x,int i) {
    while(i-1-len[x]<0 || s[i]!=s[i-1-len[x]]) x=fail[x];
    return x;
}
void solve() {
    cin>>n>>s;
    s=s+s;
    fail[0]=1,len[1]=-1;
    for(int i=0;i<2*n;i++) {
        int c=s[i]-'0';
        pos=getfail(cur,i);
        if(!t[pos][c]) {
            fail[++tot]=t[getfail(fail[pos],i)][c];
            len[tot]=len[pos]+2;
            t[pos][c]=tot;
        }
        cur=t[pos][c];
        if(i>=n) {
            num[cur]++;
        }
    }
    for(int i=tot;i>=2;i--) {
        int v=fail[i];
        num[v]+=num[i];
        num[v]%=mod;
    }
    for(int i=2;i<=tot;i++) if(len[i]<=n) ans+=num[i]*num[i]%mod*len[i]%mod,ans%=mod;
    cout<<ans<<endl;
}
int main() {
    ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    // int T;
    // cin>>T;
    // while(T--) 
    solve();
    return 0;
}