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

#define ll long long 
#define lll __int128
#define INF 0x3f3f3f3f
#define LNF 0x3f3f3f3f3f3f3f3fll
#define MOD 998244353
#define pii pair<int, int>
#define pll pair<ll, ll>
#define ld long double
#define fi first
#define se second
#define all(a) a.begin(), a.end()

#define N 200010

namespace PAM {
    static const int P = 3000010;
    int z, sz, last;
    int ch[P][26], len[P], fail[P], cnt[P];
    char s[P];

    int add_node(int l) {
        int cu = z ++;
        len[cu] = l;
        return cu;
    }

    int next(int x) {
        return s[sz-len[x]-1] == s[sz] ? x : next(fail[x]);
    }

    void init() {
        z = sz = 0;
        s[sz] = '$';
        memset(ch, 0, sizeof(ch));
        memset(len, 0, sizeof(len));
        memset(fail, 0, sizeof(fail));
        memset(cnt, 0, sizeof(cnt));
        last = add_node(0);
        fail[last] = add_node(-1);
    }

    void insert(char c, int flag) {
        s[++ sz] = c;
        int cur = next(last);
        if (!ch[cur][c-'0']) {
            int cu = add_node(len[cur] + 2);
            fail[cu] = ch[next(fail[cur])][c-'0'];
            ch[cur][c-'0'] = cu;
        }
        last = ch[cur][c-'0'];
        cnt[last] += flag;
    }

    ll count(int n) {
        ll res = 0;
        for (int i = z-1; i >= 0; -- i) cnt[fail[i]] = ((ll) cnt[fail[i]] + cnt[i]) % MOD;
        for (int i = 0; i < z; ++ i) {
            if (len[i] > 0 && len[i] <= n) {
                res += (ll) cnt[i] * cnt[i] % MOD * len[i] % MOD;
                res %= MOD;
            }
        }
        return res;
    }
};

int main() {
#ifdef TEST
    freopen("zz.in", "r+", stdin);
#endif
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int n; cin >> n;
    string s; cin >> s;
    s += s;
    PAM::init();
    for (int i = 0; i < s.length(); ++ i) {
        PAM::insert(s[i], i >= n);
    }
    cout << PAM::count(n) << '\n';
}