import java.io.InputStream
import java.io.PrintWriter
import java.util.*

fun PrintWriter.solve() = with(FastScanner(System.`in`)) {
    val n = nextInt()
    val b = Array(n) { nextInt() }
    val a = Array(n) { 0 }
    val max = b.max()!!
    if (max >= 10) {
        println(0)
    } else {
        dfs(a, b, 0, max)
        println(count)
    }
}

var count = 0L

fun dfs(a: Array<Int>, b: Array<Int>, i: Int, max: Int) {
    val n = a.count()
    if (i == n) {
        val a_or = Array(n) { a[0] }
        for (j in 1 until n) {
            a_or[j] = a_or[j - 1] or a[j]
        }
        if ((0 until n).all { b[it] == -1 || b[it] == a_or[it] }) count++
    } else {
        for (v in 1..max) {
            a[i] = v
            dfs(a, b, i + 1, max)
        }
    }
}

fun main() {
    val writer = PrintWriter(System.out, false)
    writer.solve()
    writer.flush()
}

class FastScanner(s: InputStream) {
    private var st = StringTokenizer("")
    private val br = s.bufferedReader()

    fun next(): String {
        while (!st.hasMoreTokens()) st = StringTokenizer(br.readLine())
        return st.nextToken()
    }

    fun nextInt() = next().toInt()
    fun nextLong() = next().toLong()
    fun nextLine() = br.readLine()
    fun nextDouble() = next().toDouble()
}