#include<bits/stdc++.h>
using namespace std;
using ll=long long;
constexpr int Mod=998244353;
constexpr int N=6000010;

struct PAM {
    static constexpr int ALPHABET_SIZE=10;
    struct Node {
        int len,link,cnt;
        array<int,ALPHABET_SIZE> next;
        Node():len{},link{},cnt{},next{} {}
    };
    vector<Node> t;
    int suff;
    string s;
    PAM() {init();}
    void init() {
        t.reserve(N);
        t.assign(2,Node());
        t[0].len=-1;
        suff=1;
        s.clear();
    }
    int newNode() {
        t.emplace_back();
        return t.size()-1;
    }
    bool add(char c) {
        int pos=s.size();
        s+=c;
        int let=c-'0';
        int cur=suff,curlen=0;
        while(true) {
            curlen=t[cur].len;
            if(pos-1-curlen>=0 && s[pos-1-curlen]==s[pos]) {
                break;
            }
            cur=t[cur].link;
        }
        if(t[cur].next[let]) {
            suff=t[cur].next[let];
            return false;
        }
        int num=newNode();
        suff=num;
        t[num].len=t[cur].len+2;
        t[cur].next[let]=num;
        if(t[num].len==1) {
            t[num].link=1;
            t[num].cnt=1;
            return true;
        }
        while(true) {
            cur=t[cur].link;
            curlen=t[cur].len;
            if(pos-1-curlen>=0 && s[pos-1-curlen]==s[pos]) {
                t[num].link=t[cur].next[let];
                break;
            }
        }
        t[num].cnt=1+t[t[num].link].cnt;
        return true;
    }
    int next(int p,int x) {return t[p].next[x];};
    int link(int p) {return t[p].link;}
    int len(int p) {return t[p].len;}
    int cnt(int p) {return t[p].cnt;}
    int size() {return t.size();}
}pam;
void Add(int &a,int b) {
    a+=b;
    if(a>=Mod) a-=Mod;
}
int add(int a,int b) {
    Add(a,b);
    return a;
}
void Mul(int &a,int b) {
    a=1LL*a*b%Mod;
}
int mul(int a,int b) {
    Mul(a,b);
    return a;
}
void solve() {
    int n;
    cin>>n;
    string s;
    cin>>s;
    vector<int> ends;
    for(auto ch: s) {
        pam.add(ch);
        ends.push_back(pam.suff);
    }
    int x1=pam.size();
    vector<int> f1(N);
    for(int v: ends)
        f1[v]++;
    vector adj(N,vector<int>());
    for(int i=2;i<x1;i++) {
        adj[pam.link(i)].push_back(i);
    }
    auto dfs1=[&](auto &&dfs1,int u)->void {
        for(int v: adj[u]) {
            dfs1(dfs1,v);
            f1[u]+=f1[v];
        }
    };
    dfs1(dfs1,1);
    for(auto ch: s) {
        pam.add(ch);
        ends.push_back(pam.suff);
    }
    int x2=pam.size();
    vector<int> f2(N);
    for(int v: ends)
        f2[v]++;
    for(int i=x1;i<x2;i++) {
        adj[pam.link(i)].push_back(i);
    }
    int ans=0;
    auto dfs2=[&](auto &&dfs2,int u)->void {
        for(int v: adj[u]) {
            dfs2(dfs2,v);
            f2[u]+=f2[v];
        }
        if(pam.len(u)<=n) Add(ans,mul(pam.len(u),mul(f2[u]-f1[u],f2[u]-f1[u])));
    };
    dfs2(dfs2,1);
    cout<<ans<<"\n";
}
int main() {
    ios::sync_with_stdio(false),cin.tie(0);
    int _=1;
    // cin>>_;
    while(_--)
        solve();
    return 0;
}