import java.io.BufferedReader
import java.io.InputStream
import java.io.InputStreamReader
import java.lang.AssertionError
import java.util.*
import kotlin.math.abs
import kotlin.math.max
import kotlin.math.min

val MOD = 1_000_000_007

class Comb(n: Int, val mod: Int) {

  val F = LongArray(n + 1)
  val I = LongArray(n + 1)
  init {
    F[0] = 1
    for (i in 1..n) {
      F[i] = F[i - 1] * i % mod
    }
    I[n] = powMod(F[n], (mod - 2).toLong(), mod)
    for (i in n - 1 downTo 0) {
      I[i] = I[i + 1] * (i + 1) % mod
    }
  }

  private fun powMod(a: Long, n: Long, mod: Int): Long {
    if (n == 0L) return 1
    val res = powMod(a * a % mod, n / 2, mod)
    return if (n % 2 == 1L) res * a % mod else res
  }

  fun comb(n: Int, k: Int): Long {
    if (n < k) return 0L
    return F[n] * I[k] % mod * I[n - k] % mod
  }

  fun perm(n: Int, k: Int): Long {
    return F[n] * I[n - k] % mod
  }

  fun inv(x: Int): Long {
    return I[x] * F[x - 1] % mod
  }

  /**
   * nのグループからk回重複ありで選ぶ組み合わせ数
   * n - 1のしきりとkの○で考える
   */
  fun H(n: Int, k: Int) = comb(n + k - 1, k)
}
fun powMod(a: Long, n: Long, mod: Int): Long {
  if (n == 0L) return 1
  val res = powMod(a * a % mod, n / 2, mod)
  return if (n % 2 == 1L) res * a % mod else res
}
class Solver(stream: InputStream, private val out: java.io.PrintWriter) {
  private val reader = BufferedReader(InputStreamReader(stream), 32768)

  private val N = ni()
  private val A = na(N)
  fun solve() {
    out.println(solve2())
  }

  fun solve2(): Long {
    var bit = 0
    var ans = 1L
    var n = 0L

    val comb = Comb(100, MOD)
    val sub1 = MOD - 1

    for (i in 0 until N) {
      n++
      if (A[i] == -1) continue

      val prev = bit
      bit = A[i]
      val C = IntArray(3)
      for (j in 0 until 30) {
        val px = prev shr j and 1
        val x = bit shr j and 1
        if (px == 0 && x == 0) {
          C[0]++ // 全部0
        }
        else if (px == 0 && x == 1) {
          C[1]++ // 1を含む
        }
        else if (px == 1 && x == 1) {
          C[2]++ // 何でもあり
        }
        else {
          return 0
        }
      }

      debug(C)

      val K1 = C[1]
      val K = C[1] + C[2]
      var sign = 1
      var v = 0L
      for (k in 0 .. K1) { // 和集合を除いたものがほしいので、開始は k=0, sign=1
        if (k == K) continue // 全部0の場合はcolの条件を満たさないので、元の集合に含まれていない
        val col = (powMod(2, (K - k).toLong(), MOD) + sub1) % MOD
        val diff = comb.comb(K1, k) * powMod(col, n, MOD) % MOD
        debug{"k:$k col:$col diff:$diff"}
        val d = (MOD + diff*sign) % MOD
        v = (v + d) % MOD
        sign *= -1
      }
      debug{"i:$i v:$v"}
      ans = ans * v % MOD

      n = 0
    }

    return ans
  }













































  private val isDebug = try {
    // なんか本番でエラーでる
    System.getenv("MY_DEBUG") != null
  } catch (t: Throwable) {
    false
  }

  private var tokenizer: StringTokenizer? = null
  private fun next(): String {
    while (tokenizer == null || !tokenizer!!.hasMoreTokens()) {
      tokenizer = StringTokenizer(reader.readLine())
    }
    return tokenizer!!.nextToken()
  }

  private fun ni() = next().toInt()
  private fun nl() = next().toLong()
  private fun ns() = next()
  private fun na(n: Int, offset: Int = 0): IntArray {
    return IntArray(n) { ni() + offset }
  }
  private fun nal(n: Int, offset: Int = 0): LongArray {
    val res = LongArray(n)
    for (i in 0 until n) {
      res[i] = nl() + offset
    }
    return res
  }

  private fun na2(n: Int, offset: Int = 0): Array<IntArray> {
    val a  = Array(2){IntArray(n)}
    for (i in 0 until n) {
      for (e in a) {
        e[i] = ni() + offset
      }
    }
    return a
  }

  private inline fun debug(msg: () -> String) {
    if (isDebug) System.err.println(msg())
  }

  /**
   * コーナーケースでエラー出たりするので、debug(dp[1])のように添え字付きの場合はdebug{}をつかうこと
   */
  private inline fun debug(a: LongArray) {
    debug { a.joinToString(" ") }
  }

  private inline fun debug(a: IntArray) {
    debug { a.joinToString(" ") }
  }

  private inline fun debug(a: BooleanArray) {
    debug { toString(a) }
  }

  private inline fun toString(a: BooleanArray) = run{a.map { if (it) 1 else 0 }.joinToString("")}

  private inline fun debugDim(A: Array<LongArray>) {
    if (isDebug) {
      for (a in A) {
        debug(a)
      }
    }
  }
  private inline fun debugDim(A: Array<IntArray>) {
    if (isDebug) {
      for (a in A) {
        debug(a)
      }
    }
  }
  private inline fun debugDim(A: Array<BooleanArray>) {
    if (isDebug) {
      for (a in A) {
        debug(a)
      }
    }
  }

  /**
   * 勝手にimport消されるのを防ぎたい
   */
  private fun hoge() {
    min(1, 2)
    max(1, 2)
    abs(-10)
  }

  private inline fun assert(b: Boolean) = run{if (!b) throw AssertionError()}
}

fun main() {
  val out = java.io.PrintWriter(System.out)
  Solver(System.`in`, out).solve()
  out.flush()
}