import sys
input = sys.stdin.readline

mod=998244353

N=int(input())

A=list(map(int,input().split()))

ANS=0
SUM=sum(A)

for a in A:
    ANS+=a*(a+1)//2

    k=(a*(a-1)*(2*a-1)//6 + a*(a-1)//2)//2

    ANS+=k

    ANS+=(SUM-a)*a*(a+1)//2

    ANS%=mod

print(ANS%mod)