using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;

namespace ARC066C
{
    class Program
    {
        static void Solve(Input input)
        {
            var n = input.NextInt();
            var a = input.NextInt(n);
            var p = new int[n];

            // 両端はn-1個
            // そこから一つ内側に行くにつれて2ずつ値が減っていく
            for (int i = 0; i < n; i++)
            {
                if (a[i] == 0)
                {
                    p[n / 2]++;
                }
                else
                {
                    p[(n - a[i]) / 2]++;
                    p[n - (n - a[i]) / 2 - 1]++;
                }
            }


            var mod = new Modulo();
            long pat = mod.Power(2, n / 2);

            // 奇数個の場合、中央は必ず0
            if (n % 2 != 0)
            {
                if (p[n / 2] != 1)
                {
                    pat = 0;
                }
            }
            // 中央以外は必ずペア
            if (!p.Take(n / 2).Concat(p.Skip(n / 2 + 1)).All(x => x == 2))
            {
                pat = 0;
            }

            Console.WriteLine(pat);
        }

        /// <summary>
        /// Mを法とする数値
        /// </summary>
        class Modulo
        {
            public int M { get; private set; }
            private bool mIsPrime;
            int[] factorials;
            int[] invs;
            int[] finvs;

            public Modulo(int m = (int)1e9 + 7)
            {
                this.M = m;
                this.mIsPrime = isPrime(m);

                factorials = Enumerable.Repeat<int>(1, 2).ToArray();
                invs = Enumerable.Repeat<int>(1, 2).ToArray();
                finvs = Enumerable.Repeat<int>(1, 2).ToArray();
            }

            [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
            public int Add(int a, int b)
            {
                return (a + b) % this.M;
            }

            [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
            public int Sub(int a, int b)
            {
                return (a + this.M - b) % this.M;
            }

            [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
            public int Mul(int a, int b)
            {
                return (int)(((long)(a % this.M) * (b % this.M)) % this.M);
            }

#if false
            /// <summary>
            /// x^y
            /// 繰り返し二乗法
            /// </summary>
            /// <param name="x"></param>
            /// <param name="y"></param>
            /// <returns></returns>
            public long Power(long x, long y)
            {
                switch (y)
                {
                    case 0: return 1;
                    case 1: return x % this.M;

                    default:
                        long z1 = Power(x, y / 2);
                        long z2 = Mul(z1, z1);

                        if ((y % 2) == 0)
                        {
                            return z2;
                        }
                        else
                        {
                            return Mul(z2, x);
                        }
                }
            }
#endif

            /// <summary>
            /// x^y
            /// 繰り返し二乗法（バイナリ）
            /// </summary>
            /// <param name="x"></param>
            /// <param name="y"></param>
            /// <returns></returns>
            public int Power(int x, int y)
            {
                var r = 1;

                while (y > 0)
                {
                    if ((y & 1) != 0)
                    {
                        r = Mul(r, x);
                    }
                    x = Mul(x, x);

                    y >>= 1;
                }

                return r;
            }

            /// <summary>
            /// aの逆元（a^-1）
            /// Mとaが互いに素である必要があるが
            /// 大抵Mが素数でa<Mなのでチェックしない
            /// </summary>
            /// <param name="a"></param>
            /// <returns></returns>
            public int Inverse(int a)
            {
                int b = this.M;
                int u = 1, v = 0;

                while (b > 0)
                {
                    int t = a / b;
                    a -= t * b;
                    swap(ref a, ref b);
                    u -= t * v;
                    swap(ref u, ref v);
                }

                u %= M;
                if (u < 0) u += this.M;

                return u;
            }

            /// <summary>
            /// a/b
            /// </summary>
            /// <param name="a"></param>
            /// <param name="b"></param>
            /// <returns></returns>
            public int Div(int a, int b)
            {
                if (!this.mIsPrime)
                {
                    throw new ArgumentException();
                }

                return Mul(a, Inverse(b));
            }

            /// <summary>
            /// a以下の階乗のテーブルを作成する
            /// </summary>
            /// <param name="a"></param>
            void factTable(int a)
            {
                if (a >= factorials.Length)
                {
                    int begin = factorials.Length;

                    Array.Resize(ref factorials, a + 1);

                    for (int i = begin; i <= a; i++)
                    {
                        factorials[i] = Mul(factorials[i - 1], i);
                    }
                }
            }

            /// <summary>
            /// a以下の逆元テーブルを作成する
            /// </summary>
            /// <param name="a"></param>
            void invTable(int a)
            {
                if (a >= invs.Length)
                {
                    int begin = invs.Length;

                    Array.Resize(ref invs, a + 1);

                    for (int i = begin; i <= a; i++)
                    {
                        invs[i] = this.M - Mul(invs[this.M % i], this.M / i);
                    }
                }
            }

            /// <summary>
            /// a以下の階乗の逆元テーブルを作成する
            /// </summary>
            /// <param name="a"></param>
            void finvTable(int a)
            {
                if (a >= finvs.Length)
                {
                    invTable(a);

                    int begin = finvs.Length;

                    Array.Resize(ref finvs, a + 1);

                    for (int i = begin; i <= a; i++)
                    {
                        finvs[i] = Mul(finvs[i - 1], invs[i]);
                    }
                }
            }

            /// <summary>
            /// nCr
            /// </summary>
            /// <param name="n"></param>
            /// <param name="r"></param>
            /// <returns></returns>
            public int Ncr(int n, int r)
            {
                if (n == r) return 1;

                if (factorials.Length <= n) factTable(n);
                if (finvs.Length <= n) finvTable(n);

                return Mul(factorials[n], Mul(finvs[r], finvs[n - r]));
            }

            /// <summary>
            /// 素数か
            /// </summary>
            /// <param name="x"></param>
            /// <returns></returns>
            static bool isPrime(long x)
            {
                if (x < 2)
                {
                    return false;
                }
                if (x == 2)
                {
                    return true;
                }
                if ((x % 2) == 0)
                {
                    return false;
                }

                long rx = (long)(Math.Sqrt(x) + 1);
                for (long n = 3; n < rx; n += 2)
                {
                    if ((x % n) == 0)
                    {
                        return false;
                    }
                }

                return true;
            }

            static void swap<T>(ref T a, ref T b)
            {
                T temp = a;
                a = b;
                b = temp;
            }
        }

        #region Main
        public static void Main(string[] args)
        {
            // 出力が少ないときはこれをセットする方が時間かかるけれど
            // その場合は出力がボトルネックになっていないので、まあ良しとする
            var needsFlushOutput = true;
            if (needsFlushOutput)
            {
                // 細かく出力しないようにする
                var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
                Console.SetOut(sw);
            }

            // 通常は引数無しで、ファイルから読み出したい場合はpath指定する
            var input = new Input();
            // 仮想的に標準入力をセットする
            //input.SetText("");

            Solve(input);

            Console.Out.Flush();
        }
        #endregion

        #region Competitive Template
#pragma warning disable CS0414
        static readonly int MOD = (int)1e9 + 7;
#pragma warning restore CS0414

        class Input
        {
            // 変な改行コードがたまに混じっているので、一応セパレート指定する
            // スペース単独指定の方がもちろん早い
            static readonly char[] separator = { ' ', '\r', '\n' };
            Queue<string> q { get; set; }
            StreamReader sr;

            /// <summary>
            /// 特定のファイルから読み出したい場合はpath指定する
            /// </summary>
            /// <param name="path"></param>
            public Input(string path = "")
            {
                q = new Queue<string>();

                if (string.IsNullOrEmpty(path))
                {
                    sr = new StreamReader(Console.OpenStandardInput());
                }
                else
                {
                    sr = new StreamReader(path);
                }
            }

            /// <summary>
            /// 入力予約
            /// </summary>
            /// <param name="items"></param>
            public void SetText(IEnumerable<string> items)
            {
                foreach (var item in items)
                {
                    SetText(item);
                }
            }

            /// <summary>
            /// 入力予約
            /// </summary>
            /// <param name="s"></param>
            /// <returns></returns>
            public bool SetText(string s)
            {
                if (s == null) return false;

                foreach (var elem in s.Trim().Split(separator, StringSplitOptions.RemoveEmptyEntries))
                {
                    q.Enqueue(elem);
                }

                return true;
            }

            /// <summary>
            /// 内部queueに入力からの値をsplitして格納する
            /// </summary>
            /// <returns></returns>
            bool read()
            {
                var s = sr.ReadLine();
                if (s == null) return false;

                foreach (var elem in s.Trim().Split(separator, StringSplitOptions.RemoveEmptyEntries))
                {
                    q.Enqueue(elem);
                }

                if (!q.Any()) return read();

                return true;
            }

            /// <summary>
            /// 次のstringを一つ読み込む
            /// </summary>
            /// <returns></returns>
            public string Next()
            {
                if (!q.Any())
                {
                    if (!read())
                    {
                        return "";
                    }
                }

                return q.Dequeue();
            }

            /// <summary>
            /// 指定個数queueにたまるまでenqueueし続ける
            /// </summary>
            /// <param name="n"></param>
            /// <returns></returns>
            bool accumulate(int n)
            {
                while (q.Count() < n)
                {
                    if (!read()) return false;
                }

                return true;
            }

            public int NextInt() => int.Parse(Next());
            public long NextLong() => long.Parse(Next());
            public double NextDouble() => double.Parse(Next());

            /// <summary>
            /// n個の要素をparseして、それぞれにoffsetをaddした配列を返す
            /// </summary>
            /// <typeparam name="T"></typeparam>
            /// <param name="n"></param>
            /// <param name="offset"></param>
            /// <param name="parse"></param>
            /// <param name="add"></param>
            /// <returns></returns>
            T[] NextT<T>(int n, T offset, Func<string, T> parse, Func<T, T, T> add)
            {
                if (!accumulate(n)) return null;

                var a = new T[n];

                for (int i = 0; i < n; i++)
                    a[i] = add(parse(q.Dequeue()), offset);

                return a;
            }

            public string[] Next(int n) => NextT(n, "", x => x, (x, y) => x);
            public int[] NextInt(int n, int offset = 0) => NextT(n, offset, int.Parse, (x, y) => x + y);
            public long[] NextLong(int n, long offset = 0) => NextT(n, offset, long.Parse, (x, y) => x + y);
            public double[] NextDouble(int n, double offset = 0.0) => NextT(n, offset, double.Parse, (x, y) => x + y);
        }

        static class Utils
        {
            public static void Print<T>(IEnumerable<T> ie, string sep = " ") => Console.WriteLine(string.Join(sep, ie));
            public static void Print<T>(params T[] objs) => Print(objs);
            public static T Max<T>(params T[] objs) => objs.Max();
            public static T Min<T>(params T[] objs) => objs.Min();

            public static void Swap<T>(ref T x, ref T y) where T : struct { var t = x; x = y; y = t; }
            public static void Swap<T>(IList<T> list, int i, int j) where T : struct { var t = list[i]; list[i] = list[j]; list[j] = t; }

            /// <summary>
            /// vでfillされたT[d1][d2]配列を作成する
            /// </summary>
            /// <typeparam name="T"></typeparam>
            /// <param name="d1"></param>
            /// <param name="d2"></param>
            /// <param name="v"></param>
            /// <returns></returns>
            public static T[][] Create2DArray<T>(int d1, int d2, T v = default(T))
            {
                return
                    Enumerable.Repeat(0, d1).Select(_ =>
                    Enumerable.Repeat(v, d2).ToArray()).ToArray();
            }

            /// <summary>
            /// vでfillされたT[d1][d2][d3]配列を作成する
            /// </summary>
            /// <typeparam name="T"></typeparam>
            /// <param name="d1"></param>
            /// <param name="d2"></param>
            /// <param name="d3"></param>
            /// <param name="v"></param>
            /// <returns></returns>
            public static T[][][] Create3DArray<T>(int d1, int d2, int d3, T v = default(T))
            {
                return
                    Enumerable.Repeat(0, d1).Select(_ =>
                    Enumerable.Repeat(0, d2).Select(__ =>
                     Enumerable.Repeat(v, d3).ToArray()).ToArray()).ToArray();
            }
        }
        #endregion
    }
}


Measured memory_bytes: 21472