"""

A1+A3 , A2+A4 , A3+A

"""

import sys
from sys import stdin


def nCrB(n,r):

    binum = bi[n] - bi[r] - bi[n-r]
    if binum == 0:
        return 1
    else:
        return 0

mod = 998244353

N = int(stdin.readline())

bi = [0] * (N+1)
for i in range(1,30):
    x = 2**i
    for j in range(x,N+1,x):
        bi[j] += 1
for i in range(N):
    bi[i+1] += bi[i]

B = list(map(int,stdin.readline().split()))

C = [nCrB(N-1 , i) for i in range(N)]

dp = [1,0]

for i in range(N):

    ndp = [0,0]
    if B[i] == 0 or B[i] == -1:
        ndp[0] += dp[0]
        ndp[1] += dp[1]

    if B[i] == 1 or B[i] == -1:
        ndp[0 ^ C[i]] += dp[0]
        ndp[1 ^ C[i]] += dp[1]

    ndp[0] %= mod
    ndp[1] %= mod

    dp = ndp

print (dp[1] % mod)