import sys
input = sys.stdin.readline
N = int(input())
a = list(map(int, input().split()))
mod = 998244353

class Factorial:
  def __init__(self, n, mod):
    self.mod = mod
    self.f = [1]
    for i in range(1, n + 1): self.f.append(self.f[-1] * i % mod)
    self.i = [pow(self.f[-1], mod - 2, mod)]
    for i in range(1, n + 1)[: : -1]: self.i.append(self.i[-1] * i % mod)
    self.i.reverse()
  def factorial(self, i): return self.f[i]
  def ifactorial(self, i): return self.i[i]
  def combi(self, n, k): return self.f[n] * self.i[n - k] % self.mod * self.i[k] % self.mod
  def permi(self, n, k): return self.f[n] * self.i[n - k] % self.mod

f = Factorial(N, 2)

def lucas(n, k):
  res = 1
  while n and k:
    res &= f.combi(n % 2, k % 2)
    n >>= 1
    k >>= 1
  return res

dp = [0] * 2
dp[0] = 1
for i in range(N):
  if a[i] == 1:
    c = lucas(N - 1, i)
    if c: dp[0], dp[1] = dp[1], dp[0]
  if a[i] == -1:
    c = lucas(N - 1, i)
    if c: dp[0], dp[1] = dp[0] * 2 % mod, dp[1] * 2 % mod
    else: dp[0], dp[1] = (dp[0] + dp[1]) % mod, (dp[0] + dp[1]) % mod
print(dp[-1])