MOD = 998244353

n = int(input())
a = list(map(int, input().split()))

result = 0

for i in range(n):
    ai = a[i]
    denominator = ai
    valid = True
    for j in range(n):
        if i == j:
            continue
        aj = a[j]
        diff = aj * aj - ai * ai
        if diff == 0:
            valid = False
            break
        denominator = (denominator * diff) % MOD
    if not valid:
        continue
    denominator %= MOD
    if denominator == 0:
        continue
    inv = pow(denominator, MOD-2, MOD)
    result = (result + inv) % MOD

print(result)