MOD = 998244353

N = int(input())
C = list(map(int, input().split()))

fac = [1]
for i in range(1, N + 1):
    fac.append(fac[-1] * i % MOD)



minus = len([c for c in C if c < 0])
zero = len([c for c in C if c == 0])
plus = len([c for c in C if c > 0])

pow_minus = pow(2, minus - 1, MOD) if minus > 0 else 1
pow_plus = pow(2, plus - 1, MOD) if plus > 0 else 1

print(pow_minus * pow_plus % MOD * fac[3 - [minus, zero, plus].count(0)] % MOD)