#include<bits/stdc++.h>
#define cs const
#define pb push_back
using namespace std;
cs int mod = 998244353; 
cs int N = 6e6 + 5; 

int n;
string S;
namespace pam {
    int ch[N][10], len[N], lk[N], rp, las, nd; 
    int sz[N], ans; 
    int sz0[N]; 
    void init() {
        rp = 0;
        las = nd = 1; 
        len[1] = -1;
        lk[0] = 1; 
    }
    int jmp(int x) {
        while(S[rp - len[x] - 1] != S[rp]) x = lk[x]; return x;
    }
    void ins(int c) {
        ++ rp; 
        int p = jmp(las);
        if(!ch[p][c]) {
            int x = ++ nd; 
            len[x] = len[p] + 2;
            lk[x] = ch[jmp(lk[p])][c];
            ch[p][c] = x; 
        }
        las = ch[p][c];
        if(rp <= n) ++ sz0[las];
        ++ sz[las];
    }
    vector <int> e[N];
    void dfs0(int u) {
        for(int v : e[u]) 
            dfs0(v), sz0[u] += sz0[v];
    }
    void dfs(int u) {
        for(int v : e[u]) 
            dfs(v), sz[u] += sz[v]; 
        if(len[u] > 0 && len[u] <= n) {
            int s = sz[u] - sz0[u];
            ans = (ans + 1ll * s * s % mod * len[u] % mod) % mod; 
        }
    }
    void work0() {
        for(int i = 0; i <= nd; i++) 
            if(i != 1) e[lk[i]].pb(i);
        dfs0(1);
        for(int i = 0; i <= nd; i++) e[i].clear();
    }
    int work() {
        ans = 0; 
        for(int i = 0; i <= nd; i++) 
            if(i != 1) e[lk[i]].pb(i);
        dfs(1);
        for(int i = 0; i <= nd; i++) e[i].clear();
        return ans; 
    }
}

int main() {
    #ifdef zqj
    freopen("1.in","r",stdin);
    #endif
    ios :: sync_with_stdio(0), cin.tie(0);
    cin >> n >> S; 
    S = '#' + S + S; 
    pam :: init();
    for(int i = 1; i <= n + n; i++) {
        pam :: ins(S[i] - '0'); 
        if(i == n) {
            pam :: work0();
        }
    }
    cout << pam :: work()<< '\n';
    return 0; 
}