#include <bits/stdc++.h>
using namespace std;

const int N = 6e6 + 10, P = 998244353;

int trie[N][10], nxt[N], len[N], cnt[N], cv = 2;
int sum[N];

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

    int n;
    string s;
    cin >> n >> s;
    s = "#" + s + s;
    nxt[1] = 1;
    len[1] = -1;
    nxt[2] = 1;
    len[2] = 0;
    for(int i = 1, j = 2; i < s.size(); i ++) {
        while(s[i] != s[i - len[j] - 1]) j = nxt[j];
        if(!trie[j][s[i] - '0']) {
            trie[j][s[i] - '0'] = ++ cv;
            len[cv] = len[j] + 2;
            for(int &k = (nxt[cv] = nxt[j]); s[i] != s[i - len[k] - 1]; k = nxt[k]);
            if(nxt[cv] != j) nxt[cv] = trie[nxt[cv]][s[i] - '0'];
            else nxt[cv] = 2;
        }
        j = trie[j][s[i] - '0'];
        if(i > n) cnt[j] ++;
    }

    int ans = 0;
    for(int i = cv; i > 1; i --) {
        (cnt[nxt[i]] += cnt[i]) %= P;
        if(len[i] <= n) ans = (ans + (long long)(cnt[i] - sum[i] + P) * (cnt[i] - sum[i] + P) % P * len[i]) % P;
    }
    cout << ans;
}