#!usr/bin/env python3
from collections import defaultdict, deque
from heapq import heappush, heappop
from itertools import permutations, accumulate
import sys
import math
import bisect
def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def IR(n):
    return [I() for _ in range(n)]
def LIR(n):
    return [LI() for _ in range(n)]

sys.setrecursionlimit(1000000)
mod = 998244353

def main():
    def lucas(a,b):
        return 1*(a&b == b)

    n = I()
    b = LI()
    c = [lucas(n-1,i) for i in range(n)]
    dp = [0]*2
    dp[0] = 1
    for bi,ci in zip(b,c):
        ndp = [0]*2
        for j in range(2):
            for i in range(2):
                if bi >= 0 and bi != i:
                    continue
                if ci:
                    nj = j^i
                else:
                    nj = j
                ndp[nj] = (ndp[nj]+dp[j])%mod
        dp = ndp
    print(dp[1])
    return


if __name__ == "__main__":
    main()