MOD = 998244353
X = int(input())
Y = list(map(int,input().split()))
SUM = sum(Y)

def sigma_j(n):
    return n * (n+1) * pow(2,-1,MOD) % MOD

def sigma_jj(n):
    return n * (n+1) * (2*n+1) * pow(6,-1,MOD) % MOD

from0 = sum(i * (i+1) // 2 for i in Y)
ans = from0 * (SUM+1)
for i in range(X):
    
    """
    for j in range(Y[i]):
        ans += ((SUM+1-(j+1)) - (j+1)) * (j+1)
    
    = (SUM+1 - 2*(j+1)) * (j+1)
    = (SUM+1) * (j+1) - 2 * (j+1)**2
    """

    ans += (SUM+1) * sigma_j(Y[i])
    ans -= 2 * sigma_jj(Y[i])
    ans %= MOD
    
print(ans * pow(2,-1,MOD) % MOD)