#include <iostream>
#include <vector>
#include <atcoder/modint>

using mint = atcoder::modint998244353;

int main() {
    int N;
    std::cin >> N;
    std::vector<int> A(N);
    mint rs = 1;
    for (int &a : A) std::cin >> a, rs += a;
    mint result = 0;
    for (int a : A) {
        result += mint(a + 1) * a / 2 * (rs - a);
        result += mint(a - 1) * a * (a + 1) / 6;
    }
    std::cout << result.val() << std::endl;
}