#include <bits/stdc++.h>
using namespace std;
#define fo(i,j,k) for(int i=(j),end_i=(k);i<=end_i;i++)
#define ff(i,j,k) for(int i=(j),end_i=(k);i< end_i;i++)
#define fd(i,j,k) for(int i=(j),end_i=(k);i>=end_i;i--)
#define all(x) (x).begin(),(x).end()
#define cle(x) memset(x,0,sizeof(x))
#define lowbit(x) ((x)&-(x))
#define VI vector<int>
#define ll long long
#define ull unsigned ll
#define lll __int128
#define db double
#define lb long db
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define endl "\n"
template<class T>inline void read(T &x) {
    x=0; char ch=getchar(); bool f=0;
    for(;ch<'0'||ch>'9';ch=getchar()) f|=(ch=='-');
    for(;ch>='0'&&ch<='9';ch=getchar()) x=x*10+(ch^48);
    if(f) x=-x;
}
template<class T, class... V>
inline void read(T &a, V&... b){read(a); read(b...);}
#ifndef ONLINE_JUDGE
#define debug(x) cerr<<#x<<"="<<x<<endl
#define debugv(x) cerr<<#x<<" : "; ff(i,0,(x).size()) cerr<<(x)[i]<<(i==(x).size()-1?'\n':' ')
#else
#define debug(x)
#define debugv(x)
#endif
mt19937_64 rnd(chrono::steady_clock::now().time_since_epoch().count());

const ll mod = 998244353;
inline ll Pow(ll x,ll y) {
    ll ans = 1;
    for(; y; y >>= 1, x = x * x % mod)
        if(y & 1)
            ans = ans * x % mod;
    return ans;
}
inline ll Add(ll x,ll y) {
    x += y;
    return (x >= mod) ? x - mod : x;
}
inline ll Dec(ll x,ll y) {
    x -= y;
    return (x < 0) ? x + mod : x;
}
inline ll Mul(ll x,ll y) {
    return 1ll * x * y % mod;
}

const int N = 6e6 + 5;
const int S = 10;
namespace PAM {
    int n,s[N],num[N],cnt,las,nex[N][S],fail[N],len[N];
    int quick[N][S];
    void init() {
        s[n=0]=len[cnt=1]=-1;
        fail[las=0]=fail[1]=1;
        for (int i = 0; i < S; i ++) {
            quick[0][i] = quick[1][i] = 1;
        }
    }

    void add(int c, bool flag) {
        s[++n] = c;
        int p = las;
        if (s[n - len[p] - 1] != s[n]) p = quick[p][c];
        if(!nex[p][c]) {
            int np = ++cnt, q = fail[p];
            len[np] = len[p]+2;
            if (s[n - len[q] - 1] != s[n]) q = quick[q][c];
            fail[np] = nex[q][c];
            memcpy(quick[np], quick[fail[np]], sizeof(quick[np]));
            quick[np][s[n - len[fail[np]]]] = fail[np];
            nex[p][c] = np;
        }
        las = nex[p][c];
        if (flag) num[las] ++;
    }

    vector<int> adj[N];
    void dfs(int u) {
        for (auto v : adj[u]) {
            dfs(v);
            num[u] += num[v];
        }
    }
    ll work(int n) {
        fo(i,0,cnt) if (i != 1) adj[fail[i]].pb(i);
        dfs(1);
        ll ans = 0;
        fo(i,2,cnt)
            if (len[i] <=n)
                ans = Add(ans, Mul(len[i], Mul(num[i], num[i])));
        return ans;
    }
}
int n;
char s[N];
int main() {
    read(n);
    scanf("%s", s + 1);
    PAM::init();
    for (int i = 1; i <= n; i ++)
        PAM::add(s[i] - '0', 0);
    for (int i = 1; i <= n; i ++)
        PAM::add(s[i] - '0', 1);
    printf("%lld\n", PAM::work(n));
    return 0;
}