mod = 998244353
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    def pow2(n):
        res = 0
        while n % 2 == 0:
            res += 1
            n //= 2
        return res

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

    dp0 = [0] * (N+1)
    dp1 = [0] * (N+1)
    dp0[0] = 1
    num2 = 0
    for i, b in enumerate(B):
        if i > 0:
            upper = pow2(N - i)
            lower = pow2(i)
            num2 += upper - lower
        elif i == N-1:
            num2 = 0
        if b == 0:
            dp0[i+1] = dp0[i]
            dp1[i+1] = dp1[i]
        elif b == 1:
            if num2:
                dp0[i + 1] = dp0[i]
                dp1[i + 1] = dp1[i]
            else:
                dp0[i + 1] = dp1[i]
                dp1[i + 1] = dp0[i]
        else:
            if num2:
                dp0[i + 1] = (dp0[i] * 2)%mod
                dp1[i + 1] = (dp1[i] * 2)%mod
            else:
                dp0[i + 1] = (dp1[i] + dp0[i]) % mod
                dp1[i + 1] = (dp0[i] + dp1[i]) % mod
    print(dp1[-1])


if __name__ == '__main__':
    main()