MOD = 998244353

X = int(input())
Y = list(map(int, input().split()))
sum_Y = sum(Y)

ans = 0

for i in range(X):
    ans += Y[i] * (Y[i] + 1) * (2 * Y[i] + 1) * pow(12, -1, MOD)
    ans %= MOD
    ans += -Y[i] * (Y[i] + 1) * pow(4, -1, MOD)
    ans %= MOD
    ans += Y[i] * (Y[i] + 1) * pow(2, -1, MOD) * (sum_Y - Y[i] + 1)
    ans %= MOD

print(ans)