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 { 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) { if (isDebug) { for (a in A) { debug(a) } } } private inline fun debugDim(A: Array) { if (isDebug) { for (a in A) { debug(a) } } } private inline fun debugDim(A: Array) { 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() }