#!/usr/bin/env pypy3

MOD = 998244353

MX = 2020202

fact = [1 for _ in range(MX)]
finv = [1 for _ in range(MX)]
for i in range(1,MX):
    fact[i] = fact[i-1]*i
    fact[i] %= MOD
finv[-1] = pow(fact[-1], -1, MOD)
for i in range(MX-2, -1, -1):
    finv[i] = finv[i+1] * (i+1)
    finv[i] %= MOD

def com(n, k):
    if n < 0 or k < 0 or n < k:
        return 0
    return fact[n] * finv[k] * finv[n-k] % MOD

n = int(input())
a = list(map(int, input().split()))
s = sum(a)
c = [0 for _ in range(n - 1)]
ps = 0
for i in range(0, n - 1):
    ps += a[i]
    c[i] = ps + i

x = 0
y = 0
f = 0
g = 0
ans = 0

for i in range(n - 1):
    while x < i:
        f -= com(y, x+1) * com(s+n-1-y, n-2-x)
        f %= MOD
        g -= com(y+1, x+2) * com(s+n-1-y, n-2-x)
        g %= MOD
        x += 1
    while y < c[i]:
        f += com(y, x) * com(s+n-2-y, n-2-x)
        f %= MOD
        g += com(y+1, x+1) * com(s+n-2-y, n-2-x)
        g %= MOD
        y += 1
    ans += com(s+n, n) * (i+1) - com(s+n-1, n-1) * (c[i]+1)
    ans += (f*(c[i]+1) - g*(i+1)) * 2
    ans %= MOD

print(ans)