#nullable enable

#region
var (_input, _iter) = (Array.Empty<string>(), 0);
T I<T>() where T : IParsable<T>
{
    while (_iter >= _input.Length) (_input, _iter) = (Console.ReadLine()!.Split(' '), 0);
    return T.Parse(_input[_iter++], null);
}
#endregion

const int Mod = 998244353;

long Power(long v, long p)
{
    var (res, k) = (1L, v);
    while (p > 0)
    {
        if ((p & 1) > 0) res = res * k % Mod;
        k = k * k % Mod;
        p >>= 1;
    }
    return res;
}
var inv2 = Power(2, Mod - 2);
var inv6 = Power(6, Mod - 2);

static T[] Range<T>(int n, Func<T> F) => Enumerable.Range(0, n).Select(_ => F()).ToArray();

var n = I<int>();
var yz = Range(n, I<long>);

var o = 0L;
var ty = 0L;
foreach (var y in yz)
{
    o = (o + y * (y + 1) % Mod * inv2) % Mod;
    ty += y;
}
ty %= Mod;
var ans = o * (ty + 1) % Mod;
foreach (var y in yz)
{
    var yb = y * (y + 1) % Mod * inv2 % Mod;
    var oe = (ty - y) % Mod;
    var t = y * (1 + y) % Mod * (y - 1) % Mod * inv6 % Mod;
    var yns = (oe * yb - t) % Mod;
    ans = (ans + yns) % Mod;
}
ans = ans * inv2 % Mod;
if (ans < 0) ans += Mod;
Console.WriteLine(ans);