using System;
using System.Collections.Generic;
using System.Linq;
using CompLib.Util;
using System.Threading;
using CompLib.Algorithm;
using CompLib.Mathematics;

public class Program
{
    private int N;
    private int[] H;
    private const int MaxH = 100000;
    private const int Lg = 16;
    private const int Len = 1 << Lg;

    public void Solve()
    {
        var sc = new Scanner();
        N = sc.NextInt();
        H = new int[2 * N];
        for (int i = 0; i < 2 * N; i++)
        {
            H[i] = sc.NextInt();
        }

        int[] cnt = new int[MaxH + 1];
        foreach (int i in H)
        {
            cnt[i]++;
        }

        ModInt[] G = new ModInt[N + 1];
        G[0] = 1;
        for (int i = 1; i <= N; i++)
        {
            G[i] = G[i - 1] * (2 * i - 1);
        }

        var q = new Queue<ModInt[]>();
        q.Enqueue(new ModInt[] {1});
        for (int i = 0; i <= MaxH; i++)
        {
            if (cnt[i] < 2) continue;
            ModInt[] b = new ModInt[cnt[i] / 2 + 1];
            for (int j = 0; 2 * j <= cnt[i]; j++)
            {
                b[j] = Combinatorics.C(cnt[i], 2 * j) * G[j];
            }

            q.Enqueue(b);
        }

        while (q.Count > 1)
        {
            var v1 = q.Dequeue();
            var v2 = q.Dequeue();
            FastFourierTransform.Convolution(ref v1, v2);
            q.Enqueue(v1);
        }

        var a = q.Dequeue();
        ModInt ans = 0;

        for (int i = 0; i <= N && i < a.Length; i++)
        {
            // Console.WriteLine($"{i} {a[i]} {tmp}");
            ans += a[i] * G[N - i] * (i % 2 == 0 ? 1 : -1);
        }

        Console.WriteLine(ans);
    }

    public static void Main(string[] args) => new Program().Solve();
    // public static void Main(string[] args) => new Thread(new Program().Solve, 1 << 27).Start();
}

namespace CompLib.Algorithm
{
    using System;
    using System.Numerics;

    public static class FastFourierTransform
    {
        private const int E = 23;
        public static readonly ModInt O = new ModInt(31);

        // private const int E = 20;
        // public static readonly ModInt O = new ModInt(646);
        // public static readonly ModInt InvO = new ModInt(208611436);

        // Z[i] 1の原始2^i乗根
        public static readonly ModInt[] Z;
        public static readonly ModInt[] InvZ;

        static FastFourierTransform()
        {
            Z = new ModInt[E + 1];
            InvZ = new ModInt[E + 1];
            Z[E] = O;
            InvZ[E] = ModInt.Inverse(O);
            for (int i = E - 1; i >= 0; i--)
            {
                Z[i] = Z[i + 1] * Z[i + 1];
                InvZ[i] = InvZ[i + 1] * InvZ[i + 1];
            }
        }

        /// <summary>
        /// a,bからc[k]=Σ(a[i]*b[k-i])を求め、aに代入
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        public static void Convolution(ref ModInt[] a, ModInt[] b)
        {
            int sz = a.Length + b.Length - 1;
            int len = 1;
            int lg = 0;
            while (len < sz)
            {
                lg++;
                len *= 2;
            }

            Array.Resize(ref a, len);
            Transform(a, lg, len, false);
            Array.Resize(ref b, len);
            Transform(b, lg, len, false);
            for (int i = 0; i < len; i++)
            {
                a[i] *= b[i];
            }

            Transform(a, lg, len, true);
            var invLen = ModInt.Inverse(len);
            for (int i = 0; i < sz; i++)
            {
                a[i] *= invLen;
            }

            Array.Resize(ref a, sz);
        }

        public static void Transform(ModInt[] a, int lg, int len, bool inverse)
        {
            for (int i = 0; i < len; i++)
            {
                int rev = BitsReverse(i, lg);
                if (i < rev)
                {
                    var tmp = a[i];
                    a[i] = a[rev];
                    a[rev] = tmp;
                }
            }

            for (int i = 1; i <= lg; i++)
            {
                int b = 1 << (i - 1);
                ModInt z = 1;
                for (int j = 0; j < b; j++)
                {
                    for (int k = j; k < len; k += (b << 1))
                    {
                        ModInt t = z * a[k + b];
                        ModInt u = a[k];
                        a[k] = u + t;
                        a[k + b] = u - t;
                    }

                    z *= inverse ? InvZ[i] : Z[i];
                }
            }
        }

        /// <summary>
        /// lg桁のbit列vのbitを逆順にする
        /// </summary>
        /// <param name="v"></param>
        /// <param name="lg"></param>
        /// <returns></returns>
        public static int BitsReverse(int v, int lg)
        {
            int result = 0;
            for (int i = 0; i < lg; i++)
            {
                if (((1 << i) & v) > 0)
                {
                    result |= (1 << (lg - 1 - i));
                }
            }

            return result;
        }

        /// <summary>
        /// a,bからc[k]=Σ(a[i]*b[k-i])を求める
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        public static double[] Convolution(double[] a, double[] b)
        {
            int n = 1;
            while (n < (a.Length + b.Length))
            {
                n *= 2;
            }

            var compA = new Complex[n];
            for (int i = 0; i < a.Length; i++)
            {
                compA[i] = new Complex(a[i], 0);
            }

            var compB = new Complex[n];
            for (int i = 0; i < b.Length; i++)
            {
                compB[i] = new Complex(b[i], 0);
            }

            Complex[] hatG = Transform(compA);
            Complex[] hatH = Transform(compB);
            Complex[] hatF = new Complex[n];
            for (int i = 0; i < n; i++)
            {
                hatF[i] = hatG[i] * hatH[i];
            }

            Complex[] nF = Transform(hatF, true);

            double[] f = new double[n];
            for (int i = 0; i < n; i++)
            {
                f[i] = nF[i].Real / n;
            }

            return f;
        }

        public static Complex[] DiscreteFourierTransform(Complex[] a, bool inverse = false)
        {
            int n = 1;
            while (n < a.Length)
            {
                n *= 2;
            }

            Complex[] aa = new Complex[n];
            for (int i = 0; i < a.Length; i++)
            {
                aa[i] = a[i];
            }

            return Transform(aa, inverse);
        }

        // f(x) = Σa_i*x^i の離散フーリエ変換
        // deg(f)は2羃
        private static Complex[] Transform(Complex[] a, bool inverse = false)
        {
            int n = a.Length;
            if (n == 1)
            {
                return a;
            }

            Complex[] a0 = new Complex[n / 2];
            Complex[] a1 = new Complex[n / 2];
            for (int i = 0; i < n / 2; i++)
            {
                a0[i] = a[2 * i];
                a1[i] = a[2 * i + 1];
            }

            Complex[] hatF0 = Transform(a0, inverse);
            Complex[] hatF1 = Transform(a1, inverse);

            // ζ_n
            Complex zetaN = Zeta(inverse ? -n : n);

            var result = new Complex[n];

            // ζ_n^i
            Complex zetaNi = 1;
            for (int i = 0; i < n; i++)
            {
                result[i] = hatF0[i % (n / 2)] + zetaNi * hatF1[i % (n / 2)];
                zetaNi *= zetaN;
            }

            return result;
        }

        private static Complex Zeta(int n)
        {
            double rad = 2 * Math.PI / n;
            double re = Math.Cos(rad);
            double im = Math.Sin(rad);
            return new Complex(re, im);
        }
    }
}

namespace CompLib.Mathematics
{
    public static partial class Combinatorics
    {
        private const int Max = 5000000;
        private static ModInt[] F;

        static Combinatorics()
        {
            F = new ModInt[Max + 1];
            F[0] = 1;
            for (int i = 1; i <= Max; i++)
            {
                F[i] = F[i - 1] * i;
            }
        }

        /// <summary>
        /// 階乗 n!
        /// </summary>
        /// <param name="n"></param>
        /// <returns></returns>
        public static ModInt Factorial(int n)
        {
            return F[n];
        }

        /// <summary>
        /// 順列
        /// </summary>
        /// <remarks>
        /// n個からm個選んで並べる
        /// </remarks>
        /// <param name="n"></param>
        /// <param name="m"></param>
        /// <returns></returns>
        public static ModInt P(int n, int m)
        {
            return F[n] * ModInt.Inverse(F[n - m]);
        }

        /// <summary>
        /// 組み合わせ
        /// </summary>
        /// <remarks>
        /// n個からm個取り出す
        /// </remarks>
        /// <param name="n"></param>
        /// <param name="m"></param>
        /// <returns></returns>
        public static ModInt C(int n, int m)
        {
            if (n < m) return 0;
            return F[n] * ModInt.Inverse(F[n - m] * F[m]);
        }

        /// <summary>
        /// 重複組み合わせ
        /// </summary>
        /// <remarks>
        /// n種類のものから重複を許して r個選ぶ
        /// </remarks>
        /// <param name="n"></param>
        /// <param name="m"></param>
        /// <returns></returns>
        public static ModInt H(int n, int r)
        {
            return C(n + r - 1, r);
        }
    }
}

// https://bitbucket.org/camypaper/complib
namespace CompLib.Mathematics
{
    #region ModInt

    /// <summary>
    /// [0,<see cref="Mod"/>) までの値を取るような数
    /// </summary>
    public struct ModInt
    {
        /// <summary>
        /// 剰余を取る値．
        /// </summary>
        // public const long Mod = (int) 1e9 + 7;
        public const long Mod = 998244353;

        /// <summary>
        /// 実際の数値．
        /// </summary>
        public long num;

        /// <summary>
        /// 値が <paramref name="n"/> であるようなインスタンスを構築します．
        /// </summary>
        /// <param name="n">インスタンスが持つ値</param>
        /// <remarks>パフォーマンスの問題上，コンストラクタ内では剰余を取りません．そのため，<paramref name="n"/> ∈ [0,<see cref="Mod"/>) を満たすような <paramref name="n"/> を渡してください．このコンストラクタは O(1) で実行されます．</remarks>
        public ModInt(long n)
        {
            num = n;
        }

        /// <summary>
        /// このインスタンスの数値を文字列に変換します．
        /// </summary>
        /// <returns>[0,<see cref="Mod"/>) の範囲内の整数を 10 進表記したもの．</returns>
        public override string ToString()
        {
            return num.ToString();
        }

        public static ModInt operator +(ModInt l, ModInt r)
        {
            l.num += r.num;
            if (l.num >= Mod) l.num -= Mod;
            return l;
        }

        public static ModInt operator -(ModInt l, ModInt r)
        {
            l.num -= r.num;
            if (l.num < 0) l.num += Mod;
            return l;
        }

        public static ModInt operator *(ModInt l, ModInt r)
        {
            return new ModInt(l.num * r.num % Mod);
        }

        public static implicit operator ModInt(long n)
        {
            n %= Mod;
            if (n < 0) n += Mod;
            return new ModInt(n);
        }

        /// <summary>
        /// 与えられた 2 つの数値からべき剰余を計算します．
        /// </summary>
        /// <param name="v">べき乗の底</param>
        /// <param name="k">べき指数</param>
        /// <returns>繰り返し二乗法により O(N log N) で実行されます．</returns>
        public static ModInt Pow(ModInt v, long k)
        {
            return Pow(v.num, k);
        }

        /// <summary>
        /// 与えられた 2 つの数値からべき剰余を計算します．
        /// </summary>
        /// <param name="v">べき乗の底</param>
        /// <param name="k">べき指数</param>
        /// <returns>繰り返し二乗法により O(N log N) で実行されます．</returns>
        public static ModInt Pow(long v, long k)
        {
            long ret = 1;
            for (k %= Mod - 1; k > 0; k >>= 1, v = v * v % Mod)
                if ((k & 1) == 1)
                    ret = ret * v % Mod;
            return new ModInt(ret);
        }

        /// <summary>
        /// 与えられた数の逆元を計算します．
        /// </summary>
        /// <param name="v">逆元を取る対象となる数</param>
        /// <returns>逆元となるような値</returns>
        /// <remarks>法が素数であることを仮定して，フェルマーの小定理に従って逆元を O(log N) で計算します．</remarks>
        public static ModInt Inverse(ModInt v)
        {
            return Pow(v, Mod - 2);
        }
    }

    #endregion

    #region Binomial Coefficient

    public class BinomialCoefficient
    {
        public ModInt[] fact, ifact;

        public BinomialCoefficient(int n)
        {
            fact = new ModInt[n + 1];
            ifact = new ModInt[n + 1];
            fact[0] = 1;
            for (int i = 1; i <= n; i++)
                fact[i] = fact[i - 1] * i;
            ifact[n] = ModInt.Inverse(fact[n]);
            for (int i = n - 1; i >= 0; i--)
                ifact[i] = ifact[i + 1] * (i + 1);
            ifact[0] = ifact[1];
        }

        public ModInt this[int n, int r]
        {
            get
            {
                if (n < 0 || n >= fact.Length || r < 0 || r > n) return 0;
                return fact[n] * ifact[n - r] * ifact[r];
            }
        }

        public ModInt RepeatedCombination(int n, int k)
        {
            if (k == 0) return 1;
            return this[n + k - 1, k];
        }
    }

    #endregion
}


namespace CompLib.Util
{
    using System;
    using System.Linq;

    class Scanner
    {
        private string[] _line;
        private int _index;
        private const char Separator = ' ';

        public Scanner()
        {
            _line = new string[0];
            _index = 0;
        }

        public string Next()
        {
            if (_index >= _line.Length)
            {
                string s;
                do
                {
                    s = Console.ReadLine();
                } while (s.Length == 0);

                _line = s.Split(Separator);
                _index = 0;
            }

            return _line[_index++];
        }

        public string ReadLine()
        {
            _index = _line.Length;
            return Console.ReadLine();
        }

        public int NextInt() => int.Parse(Next());
        public long NextLong() => long.Parse(Next());
        public double NextDouble() => double.Parse(Next());
        public decimal NextDecimal() => decimal.Parse(Next());
        public char NextChar() => Next()[0];
        public char[] NextCharArray() => Next().ToCharArray();

        public string[] Array()
        {
            string s = Console.ReadLine();
            _line = s.Length == 0 ? new string[0] : s.Split(Separator);
            _index = _line.Length;
            return _line;
        }

        public int[] IntArray() => Array().Select(int.Parse).ToArray();
        public long[] LongArray() => Array().Select(long.Parse).ToArray();
        public double[] DoubleArray() => Array().Select(double.Parse).ToArray();
        public decimal[] DecimalArray() => Array().Select(decimal.Parse).ToArray();
    }
}

Measured memory_bytes: 85852