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

using std::cin;
using std::cout;
using std::vector;

using mint = atcoder::modint998244353;

int main() {
    int X; cin >> X;
    vector<int> Y(X);
    for (int i = 0; i < X; i++) {
        cin >> Y[i];
    }

    mint sum_Y = 0;
    for (int i = 0; i < X; i++) {
        sum_Y += mint(Y[i]);
    }

    mint ans = 0;
    for (int i = 0; i < X; i++) {
        ans += mint(Y[i]).pow(2) * mint(Y[i] - 1) / 2;
        ans -= mint(Y[i]) * (mint(Y[i]) - 1) * (2 * mint(Y[i]) - 1) / 6;
        ans += mint(Y[i]) * (mint(Y[i]) + 1) * (sum_Y + 1 - mint(Y[i])) / 2;
    }

    cout << ans.val() << "\n";
}