using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Threading;
using System.Runtime.CompilerServices;
using System.Text;
using System.Diagnostics;
using System.Numerics;
using static System.Console;
using static System.Convert;
using static System.Math;
using static Template;
using SC = FastScanner;

public partial class Solver
{
    public void Solve()
    {
        ModInt.Build(100100);
        //二重階乗
        var G = new ModInt[100100];G[0] = 1;
        for (int i = 0; i < 100010; i++)
        {
            G[i + 1] = G[i] * (2 * (i + 1) - 1);
        }
        var N = sc.Int;
        var ct = new int[100100];
        for (int i = 0; i < N * 2; i++) ct[sc.Int]++;
        var deq = new Deque<ModInt[]>();
        for (int i = 0; i < ct.Length; i++)
        {
            if (ct[i] == 0) continue;
            ModInt s = 1;var C = new ModInt[ct[i] / 2 + 1];
            for(int j=0;j<=ct[i]/2;j++)
            {
                //iを用いて、身長が等しいペアをj組作る場合の数
                C[j] = s * ModInt.Comb(ct[i],2*j) * G[j];
                s = -s;
            }
            deq.PushHead(C);
        }
        //要素間のマージ
        while (deq.Count > 1)
        {
            //ある要素が次にみられるのは|deq|回後で|deq|は半分になっていくので各要素についてO(logN)回
            deq.PushTail(NTT.Convlution(deq.PopHead(), deq.PopHead()));
        }
        ModInt res = 0;
        //包除原理
        for (int i = 0; i < deq[0].Length; i++)
        {
            //身長が等しいペアをi組つくる場合の数*残りのペアの数
            res += G[N - i] * deq[0][i];
        }
        Console.WriteLine(res);
    }
}

public struct ModInt
{
    //public const long MOD = (int)1e9 + 7;
    public const long MOD = 998244353;
    public long Value { get; set; }
    public ModInt(long n = 0) { Value = n; }
    private static ModInt[] fac, inv, facinv;
    public override string ToString() => Value.ToString();
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt operator +(ModInt l, ModInt r)
    {
        l.Value += r.Value;
        if (l.Value >= MOD) l.Value -= MOD;
        return l;
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt operator -(ModInt l, ModInt r)
    {
        l.Value -= r.Value;
        if (l.Value < 0) l.Value += MOD;
        return l;
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt operator *(ModInt l, ModInt r) => new ModInt(l.Value * r.Value % MOD);
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt operator /(ModInt l, ModInt r) => l * Pow(r, MOD - 2);
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static implicit operator long(ModInt l) => l.Value;
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static implicit operator ModInt(long n)
    {
        n %= MOD; if (n < 0) n += MOD;
        return new ModInt(n);
    }

    public static ModInt Pow(ModInt m, long n)
    {
        if (n == 0) return 1;
        if (n % 2 == 0) return Pow(m * m, n >> 1);
        else return Pow(m * m, n >> 1) * m;
    }

    public static void Build(int n)
    {
        fac = new ModInt[n + 1];
        facinv = new ModInt[n + 1];
        inv = new ModInt[n + 1];
        inv[1] = fac[0] = fac[1] = facinv[0] = facinv[1] = 1;
        for (var i = 2; i <= n; i++)
        {
            fac[i] = fac[i - 1] * i;
            inv[i] = MOD - inv[MOD % i] * (MOD / i);
            facinv[i] = facinv[i - 1] * inv[i];
        }
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt Fac(int n) => fac[n];
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt Inv(int n) => inv[n];
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt FacInv(int n) => facinv[n];
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt Comb(int n, int r)
    {
        if (n < r) return 0;
        if (n == r) return 1;
        return fac[n] * facinv[r] * facinv[n - r];
    }
    public static ModInt Perm(int n, int r)
    {
        if (n < r) return 0;
        return fac[n] * facinv[n - r];
    }

}

public static class NTT
{
    const int g = 3;
    static ModInt[] sumE = null;
    static ModInt[] sumIE = null;
    static void butterfly(ModInt[] A)
    {
        int h = CeilPow2(A.Length);
        if (sumE == null)
        {
            sumE = new ModInt[30];
            ModInt[] es = new ModInt[30], ies = new ModInt[30];
            var cnt2 = CTZ((int)(ModInt.MOD - 1));
            var e = ModInt.Pow(g, (ModInt.MOD - 1) >> cnt2);
            var ie = 1 / e;
            for (int i = cnt2; i >= 2; i--)
            {
                es[i - 2] = e;
                ies[i - 2] = ie;
                e *= e;
                ie *= ie;
            }
            ModInt now = 1;
            for (int i = 0; i < cnt2 - 2; i++)
            {
                sumE[i] = es[i] * now;
                now *= ies[i];
            }
        }
        for (int ph = 1; ph <= h; ph++)
        {
            int w = 1 << (ph - 1), p = 1 << (h - ph);
            ModInt now = 1;
            for (int s = 0; s < w; s++)
            {
                int offset = s << (h - ph + 1);
                for (int i = 0; i < p; i++)
                {
                    var l = A[i + offset];
                    var r = A[i + offset + p] * now;
                    A[i + offset] = l + r;
                    A[i + offset + p] = l - r;
                }
                now *= sumE[CTZ(~s)];
            }
        }
    }
    static void butterflyInv(ModInt[] A)
    {
        int h = CeilPow2(A.Length);
        if (sumIE == null)
        {
            sumIE = new ModInt[30];
            ModInt[] es = new ModInt[30], ies = new ModInt[30];
            var cnt2 = CTZ((int)(ModInt.MOD - 1));
            var e = ModInt.Pow(g, (ModInt.MOD - 1) >> cnt2);
            var ie = 1 / e;
            for (int i = cnt2; i >= 2; i--)
            {
                es[i - 2] = e;
                ies[i - 2] = ie;
                e *= e;
                ie *= ie;
            }
            ModInt now = 1;
            for (int i = 0; i < cnt2 - 2; i++)
            {
                sumIE[i] = ies[i] * now;
                now *= es[i];
            }
        }
        for (int ph = h; ph >= 1; ph--)
        {
            int w = 1 << (ph - 1), p = 1 << (h - ph);
            ModInt inow = 1;
            for (int s = 0; s < w; s++)
            {
                int offset = s << (h - ph + 1);
                for (int i = 0; i < p; i++)
                {
                    var l = A[i + offset];
                    var r = A[i + offset + p];
                    A[i + offset] = l + r;
                    A[i + offset + p] =
                        (ModInt.MOD + l - r) * inow;
                }
                inow *= sumIE[CTZ(~s)];
            }
        }
    }
    public static ModInt[] Convlution(ModInt[] A, ModInt[] B)
    {
        int N = A.Length, M = B.Length;
        if (Min(N, M) <= 60)
        {
            if (N < M) swap(ref A, ref B);
            var res = new ModInt[N + M - 1];
            for (int i = 0; i < A.Length; i++)
                for (int j = 0; j < B.Length; j++)
                    res[i + j] += A[i] * B[j];
            return res;
        }
        var z = 1 << CeilPow2(N + M - 1);
        Array.Resize(ref A, z);
        Array.Resize(ref B, z);
        butterfly(A); butterfly(B);
        for (int i = 0; i < A.Length; i++)
            A[i] *= B[i];
        butterflyInv(A);
        Array.Resize(ref A, N + M - 1);
        var iz = (ModInt)1 / z;
        for (int i = 0; i < A.Length; i++) A[i] *= iz;
        return A;
    }
    static int CTZ(int v) => MSB(v & -v);
    static int MSB(int v)
    {
        var rt = 0;
        if ((v >> 16) > 0) { rt |= 16; v >>= 16; }
        if ((v >> 8) > 0) { rt |= 8; v >>= 8; }
        if ((v >> 4) > 0) { rt |= 4; v >>= 4; }
        if ((v >> 2) > 0) { rt |= 2; v >>= 2; }
        return rt | (v >> 1);
    }
    static int CeilPow2(int N) { int i = 0; while ((1 << i) < N) i++; return i; }
}

public class Deque<T>
{
    private T[] data;
    int offset, sz;
    public int Count { get; private set; }
    public Deque() { data = new T[sz = 16]; }
    public T this[int i]
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        get { return data[MOD(i + offset)]; }
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        set { data[MOD(i + offset)] = value; }
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public int MOD(int v) => v & (sz - 1);
    private void Extend()
    {
        var t = new T[sz << 1];
        for (var i = 0; i < sz; i++)
            t[i] = data[MOD(offset + i)];
        offset = 0;
        data = t;
        sz <<= 1;
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public void PushHead(T item)
    {
        if (Count == sz) Extend();
        data[MOD(--offset)] = item;
        Count++;
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public T PopHead()
    {
        if (Count == 0) return default(T);
        Count--;
        return data[MOD(offset++)];
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public void PushTail(T item)
    {
        if (Count == sz) Extend();
        data[MOD(Count++ + offset)] = item;
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public T PopTail()
    {
        if (Count == 0) return default(T);
        return data[MOD(--Count + offset)];
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public bool Any() => Count > 0;
    public T[] ToArray()
    {
        var rt = new T[Count];
        for (int i = 0; i < Count; i++)
            rt[i] = this[i];
        return rt;
    }
}

public class FastScanner
{
    //0x0a:LF 0x20:SPC 0x2d:- 0x30 ~ 0x39: 0 ~ 9
    static System.IO.Stream str = System.Console.OpenStandardInput();
    const int size = 1 << 10;
    static byte[] buffer = new byte[size];
    static int ptr;
    static int len;
    public int Int
    {
        get
        {
            var c = Read();
            while (c < 0x21)
            {
                c = Read();
            }
            var n = false;
            if (c == '-')
            {
                n = true;
                c = Read();
            }
            var ret = 0;
            while (c >= 0x30)
            {
                ret = ret * 10 + (c & 15);
                c = Read();
            }
            return n ? -ret : ret;
        }
    }
    public long Long
    {
        get
        {
            var c = Read();
            while (c < 0x21)
            {
                c = Read();
            }
            var n = false;
            if (c == '-')
            {
                n = true;
                c = Read();
            }
            var ret = 0L;
            while (c >= 0x30)
            {
                ret = ret * 10 + (c & 15);
                c = Read();
            }
            return n ? -ret : ret;
        }
    }
    byte Read()
    {
        if (ptr == len)
        {
            len = str.Read(buffer, 0, size);
            if (len == 0) return 0;
            ptr = 0;
        }
        return buffer[ptr++];
    }
}
#region Template
public partial class Solver
{
    public SC sc = new SC();
    static void Main(string[] args)
    {
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        var sol = new Solver();
        int testcase = 1;
        //testcase = sol.sc.Int;
        //var th = new Thread(sol.Solve, 1 << 26);th.Start();th.Join();
        while (testcase-- > 0)
            sol.Solve();
        Console.Out.Flush();
    }
}
public static class Template
{
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmin<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) > 0) { a = b; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmax<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) < 0) { a = b; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void swap<T>(ref T a, ref T b) { var t = b; b = a; a = t; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void swap<T>(this IList<T> A, int i, int j) { var t = A[i]; A[i] = A[j]; A[j] = t; }
    public static T[] Create<T>(int n, Func<T> f) { var rt = new T[n]; for (var i = 0; i < rt.Length; ++i) rt[i] = f(); return rt; }
    public static T[] Create<T>(int n, Func<int, T> f) { var rt = new T[n]; for (var i = 0; i < rt.Length; ++i) rt[i] = f(i); return rt; }
    public static void Out<T>(this IList<T> A, out T a) => a = A[0];
    public static void Out<T>(this IList<T> A, out T a, out T b) { a = A[0]; b = A[1]; }
    public static void Out<T>(this IList<T> A, out T a, out T b, out T c) { A.Out(out a, out b); c = A[2]; }
    public static void Out<T>(this IList<T> A, out T a, out T b, out T c, out T d) { A.Out(out a, out b, out c); d = A[3]; }
    public static string Concat<T>(this IEnumerable<T> A, string sp) => string.Join(sp, A);
    public static char ToChar(this int s, char begin = '0') => (char)(s + begin);
    public static IEnumerable<T> Shuffle<T>(this IEnumerable<T> A) => A.OrderBy(v => Guid.NewGuid());
    public static int CompareTo<T>(this T[] A, T[] B, Comparison<T> cmp = null) { cmp = cmp ?? Comparer<T>.Default.Compare; for (var i = 0; i < Min(A.Length, B.Length); i++) { int c = cmp(A[i], B[i]); if (c > 0) return 1; else if (c < 0) return -1; } if (A.Length == B.Length) return 0; if (A.Length > B.Length) return 1; else return -1; }
    public static string ToStr<T>(this T[][] A) => A.Select(a => a.Concat(" ")).Concat("\n");
    public static int ArgMax<T>(this IList<T> A, Comparison<T> cmp = null) { cmp = cmp ?? Comparer<T>.Default.Compare; T max = A[0]; int rt = 0; for (int i = 1; i < A.Count; i++) if (cmp(max, A[i]) < 0) { max = A[i]; rt = i; } return rt; }
    public static T PopBack<T>(this List<T> A) { var v = A[A.Count - 1]; A.RemoveAt(A.Count - 1); return v; }
    public static void Fail<T>(T s) { Console.WriteLine(s); Console.Out.Close(); Environment.Exit(0); }
}
public class Scanner
{
    public string Str => Console.ReadLine().Trim();
    public int Int => int.Parse(Str);
    public long Long => long.Parse(Str);
    public double Double => double.Parse(Str);
    public int[] ArrInt => Str.Split(' ').Select(int.Parse).ToArray();
    public long[] ArrLong => Str.Split(' ').Select(long.Parse).ToArray();
    public char[][] Grid(int n) => Create(n, () => Str.ToCharArray());
    public int[] ArrInt1D(int n) => Create(n, () => Int);
    public long[] ArrLong1D(int n) => Create(n, () => Long);
    public int[][] ArrInt2D(int n) => Create(n, () => ArrInt);
    public long[][] ArrLong2D(int n) => Create(n, () => ArrLong);
    private Queue<string> q = new Queue<string>();
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public T Next<T>() { if (q.Count == 0) foreach (var item in Str.Split(' ')) q.Enqueue(item); return (T)Convert.ChangeType(q.Dequeue(), typeof(T)); }
    public void Make<T1>(out T1 v1) => v1 = Next<T1>();
    public void Make<T1, T2>(out T1 v1, out T2 v2) { v1 = Next<T1>(); v2 = Next<T2>(); }
    public void Make<T1, T2, T3>(out T1 v1, out T2 v2, out T3 v3) { Make(out v1, out v2); v3 = Next<T3>(); }
    public void Make<T1, T2, T3, T4>(out T1 v1, out T2 v2, out T3 v3, out T4 v4) { Make(out v1, out v2, out v3); v4 = Next<T4>(); }
    public void Make<T1, T2, T3, T4, T5>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5) { Make(out v1, out v2, out v3, out v4); v5 = Next<T5>(); }
    public void Make<T1, T2, T3, T4, T5, T6>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5, out T6 v6) { Make(out v1, out v2, out v3, out v4, out v5); v6 = Next<T6>(); }
    public void Make<T1, T2, T3, T4, T5, T6, T7>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5, out T6 v6, out T7 v7) { Make(out v1, out v2, out v3, out v4, out v5, out v6); v7 = Next<T7>(); }
    public (T1, T2) Make<T1, T2>() { Make(out T1 v1, out T2 v2); return (v1, v2); }
    public (T1, T2, T3) Make<T1, T2, T3>() { Make(out T1 v1, out T2 v2, out T3 v3); return (v1, v2, v3); }
    public (T1, T2, T3, T4) Make<T1, T2, T3, T4>() { Make(out T1 v1, out T2 v2, out T3 v3, out T4 v4); return (v1, v2, v3, v4); }
}

#endregion

Measured memory_bytes: 44364