#include <bits/stdc++.h>

#include <atcoder/fenwicktree.hpp>
#include <atcoder/segtree.hpp>
#include <atcoder/modint.hpp>
#include <atcoder/dsu.hpp>
#include <atcoder/lazysegtree.hpp>

using namespace atcoder;
using namespace std;
using ll = long long;
using ull = unsigned long long;
template <class T>
using max_heap = priority_queue<T>;
template <class T>
using min_heap = priority_queue<T, vector<T>, greater<>>;
ll ll_min = numeric_limits<ll>::min();
ll ll_max = numeric_limits<ll>::max();
ll ALPHABET_N = 26;
using mint = modint998244353;
#define rep(i, n) for (ll i = (ll)0; i < (ll)n; i++)
#define rep_(i, k, n) for (ll i = (ll)k; i < (ll)n; i++)
#define all(a) a.begin(), a.end()

mint arith(ll n)
{
	return mint(n) * mint(n + 1) / 2;
}
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	ll n;
	cin >> n;
	vector<ll> Y(n);
	vector<mint> Y_(n);
	rep(i, n)
	{
		cin >> Y[i];
		Y_[i] = arith(Y[i]);
	}
	mint ans = 0;
	mint sm = accumulate(all(Y_), mint(0));
	rep(i, n)
	{
		ll y = Y[i];
		// betu
		ans += (sm - Y_[i]) * y;
		// zero
		ans += Y_[i];
		// naka
		mint my = Y[i];
		ans += (my - 1) * my * (my + 1) / 6;
	}
	cout << (ans).val() << endl;
	return 0;
}