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

#define F first
#define S second
#define sz(x) (int)x.size()

const int N = 1e6;

long long n;
long long a[N];
long long dp[N];

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        cin >> a[i];
        a[i] *= 2;
    }
    dp[1] = a[1];
    for (int i = 2; i <= n; ++i) {
        dp[i] = 0;
        for (int j = max(1, i - 10000); j < i; ++j) {
            dp[i] = max(dp[i], dp[j] + (a[i] + a[j]) / 2 * (i - j - 1) + a[i]);
        }
    }
    long long ans = dp[n];
    long long r = 1;
    n *= 2;
    const int mod = 998244353;
    long long pw = mod - 2;
    while (pw) {
        if (pw & 1) r = (r * n) % mod;
        n = (n * n) % mod;
        pw /= 2;
    }
    ans = (ans * r) % mod;
    cout << ans << '\n';
}