MOD = 998244353

X = int(input())
Y = [int(x) for x in input().split()]

sum_Y = sum(Y)
ans = 0

for i in range(X):
    ans += Y[i] ** 2 * (Y[i] - 1) // 2
    ans %= MOD

    ans -= Y[i] * (Y[i] - 1) * (2 * Y[i] - 1) // 6
    ans %= MOD

    ans += Y[i] * (Y[i] + 1) * (sum_Y + 1 - Y[i]) // 2
    ans %= MOD


print(ans)