#include <bits/stdc++.h>
using namespace std;
#include <atcoder/modint>
using mint = atcoder::modint998244353;

int main(){
	int n; cin >> n; vector<int> A(n); mint inv2 = mint(1)/2,inv6 = mint(1)/6; for (int& a:A) cin >> a;
	mint s = accumulate(A.begin(),A.end(),mint(0))+1,r = 0;
	for (int a:A) r += mint(a)*(a+1)*inv2*(s-a)+mint(a)*a*(a+1)*inv2-mint(a)*(a+1)*(2*a+1)*inv6;
	cout << r.val() << endl;
}