#include <bits/stdc++.h>
using namespace std;
using ll = long long;

#define ALL(obj) (obj).begin(),(obj).end()
template<class T> using priority_queue_reverse = priority_queue<T,vector<T>,greater<T>>;

constexpr long long MOD = 1'000'000'000LL + 7;
constexpr long long MOD2 = 998244353;
constexpr long long HIGHINF = (long long)1e18;
constexpr long long LOWINF = (long long)1e15;
constexpr long double PI = 3.1415926535897932384626433L;

template <class T> vector<T> multivector(size_t N,T init){return vector<T>(N,init);}
template <class... T> auto multivector(size_t N,T... t){return vector<decltype(multivector(t...))>(N,multivector(t...));}
template <class T> void corner(bool flg, T hoge) {if (flg) {cout << hoge << endl; exit(0);}}
template <class T, class U>ostream &operator<<(ostream &o, const map<T, U>&obj) {o << "{"; for (auto &x : obj) o << " {" << x.first << " : " << x.second << "}" << ","; o << " }"; return o;}
template <class T>ostream &operator<<(ostream &o, const set<T>&obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr) o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
template <class T>ostream &operator<<(ostream &o, const multiset<T>&obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr) o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
template <class T>ostream &operator<<(ostream &o, const vector<T>&obj) {o << "{"; for (int i = 0; i < (int)obj.size(); ++i)o << (i > 0 ? ", " : "") << obj[i]; o << "}"; return o;}
template <class T, class U>ostream &operator<<(ostream &o, const pair<T, U>&obj) {o << "{" << obj.first << ", " << obj.second << "}"; return o;}
void print(void) {cout << endl;}
template <class Head> void print(Head&& head) {cout << head;print();}
template <class Head, class... Tail> void print(Head&& head, Tail&&... tail) {cout << head << " ";print(forward<Tail>(tail)...);}
template <class T> void chmax(T& a, const T b){a=max(a,b);}
template <class T> void chmin(T& a, const T b){a=min(a,b);}
vector<string> split(const string &str, const char delemiter) {vector<string> res;stringstream ss(str);string buffer; while( getline(ss, buffer, delemiter) ) res.push_back(buffer); return res;}
int msb(int x) {return x?31-__builtin_clz(x):-1;}
void YN(bool flg) {cout << (flg ? "YES" : "NO") << endl;}
void Yn(bool flg) {cout << (flg ? "Yes" : "No") << endl;}
void yn(bool flg) {cout << (flg ? "yes" : "no") << endl;}


/*
 * @title ModInt
 * @docs md/util/ModInt.md
 */
template<long long mod> class ModInt {
public:
    long long x;
    constexpr ModInt():x(0) {}
    constexpr ModInt(long long y) : x(y>=0?(y%mod): (mod - (-y)%mod)%mod) {}
    ModInt &operator+=(const ModInt &p) {if((x += p.x) >= mod) x -= mod;return *this;}
    ModInt &operator+=(const long long y) {ModInt p(y);if((x += p.x) >= mod) x -= mod;return *this;}
    ModInt &operator+=(const int y) {ModInt p(y);if((x += p.x) >= mod) x -= mod;return *this;}
    ModInt &operator-=(const ModInt &p) {if((x += mod - p.x) >= mod) x -= mod;return *this;}
    ModInt &operator-=(const long long y) {ModInt p(y);if((x += mod - p.x) >= mod) x -= mod;return *this;}
    ModInt &operator-=(const int y) {ModInt p(y);if((x += mod - p.x) >= mod) x -= mod;return *this;}
    ModInt &operator*=(const ModInt &p) {x = (x * p.x % mod);return *this;}
    ModInt &operator*=(const long long y) {ModInt p(y);x = (x * p.x % mod);return *this;}
    ModInt &operator*=(const int y) {ModInt p(y);x = (x * p.x % mod);return *this;}
    ModInt &operator^=(const ModInt &p) {x = (x ^ p.x) % mod;return *this;}
    ModInt &operator^=(const long long y) {ModInt p(y);x = (x ^ p.x) % mod;return *this;}
    ModInt &operator^=(const int y) {ModInt p(y);x = (x ^ p.x) % mod;return *this;}
    ModInt &operator/=(const ModInt &p) {*this *= p.inv();return *this;}
    ModInt &operator/=(const long long y) {ModInt p(y);*this *= p.inv();return *this;}
    ModInt &operator/=(const int y) {ModInt p(y);*this *= p.inv();return *this;}
    ModInt operator=(const int y) {ModInt p(y);*this = p;return *this;}
    ModInt operator=(const long long y) {ModInt p(y);*this = p;return *this;}
    ModInt operator-() const {return ModInt(-x); }
    ModInt operator++() {x++;if(x>=mod) x-=mod;return *this;}
    ModInt operator--() {x--;if(x<0) x+=mod;return *this;}
    ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }
    ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }
    ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }
    ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }
    ModInt operator^(const ModInt &p) const { return ModInt(*this) ^= p; }
    bool operator==(const ModInt &p) const { return x == p.x; }
    bool operator!=(const ModInt &p) const { return x != p.x; }
    ModInt inv() const {int a=x,b=mod,u=1,v=0,t;while(b > 0) {t = a / b;swap(a -= t * b, b);swap(u -= t * v, v);} return ModInt(u);}
    ModInt pow(long long n) const {ModInt ret(1), mul(x);for(;n > 0;mul *= mul,n >>= 1) if(n & 1) ret *= mul;return ret;}
    friend ostream &operator<<(ostream &os, const ModInt &p) {return os << p.x;}
    friend istream &operator>>(istream &is, ModInt &a) {long long t;is >> t;a = ModInt<mod>(t);return (is);}
};
using modint = ModInt<MOD2>;

/*
 * @title FormalPowerSeries - 形式的冪級数
 * @docs md/math/FormalPowerSeries.md
 */
template<int mod> struct FormalPowerSeries : public vector<ModInt<mod>> {
    inline static constexpr int prime1 =1004535809;
    inline static constexpr int prime2 =998244353;
    inline static constexpr int prime3 =985661441;
    inline static constexpr int inv21  =332747959; // ModInt<mod2>(mod1).inv().x;
    inline static constexpr int inv31  =766625513; // ModInt<mod3>(mod1).inv().x;
    inline static constexpr int inv32  =657107549; // ModInt<mod3>(mod2).inv().x;
    inline static constexpr int prime12=(1002772198720536577LL) % mod;
    inline static constexpr array<int,26> pow2 = {1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768,65536,131072,262144,524288,1048576,2097152,4194304,8388608,16777216,33554432};
    using vector<ModInt<mod>>::vector;
    using Mint  = ModInt<mod>;
    using Mint1 = ModInt<prime1>;
    using Mint2 = ModInt<prime2>;
    using Mint3 = ModInt<prime3>;
    using Fps   = FormalPowerSeries<mod>;
    Fps even(void) const {Fps ret;for(int i = 0; i < this->size(); i+=2) ret.push_back((*this)[i]);return ret;}
    Fps odd(void)  const {Fps ret;for(int i = 1; i < this->size(); i+=2) ret.push_back((*this)[i]);return ret;}
    Fps minus_x(void) const {Fps ret(this->size());for(int i = 0; i < ret.size(); ++i) ret[i] = (*this)[i]*(i&1?-1:1);return ret;}
    inline Mint garner(const Mint1& b1,const Mint2& b2,const Mint3& b3) {Mint2 t2 = (b2-b1.x)*inv21;Mint3 t3 = ((b3-b1.x)*inv31-t2.x)*inv32;return Mint(prime12*t3.x+b1.x+prime1*t2.x);}
    template<int prime> inline void ntt(vector<ModInt<prime>>& f) {
        const int N = f.size(), M = N>>1;
        const int log2N = __builtin_ctz(N);
        ModInt<prime> h(3);
        vector<ModInt<prime>> g(N),base(log2N);
        for(int i=0;i<log2N;++i) base[i] = h.pow((prime - 1)/pow2[i+1]);
        for(int n=0;n<log2N;++n) {
            const int& p = pow2[log2N-n-1];
            ModInt<prime> w = 1;
            for (int i=0,k=0;i<M;i+=p,k=i<<1,w*=base[n]) {
                for(int j=0;j<p;++j) {
                    ModInt<prime> l = f[k|j],r = w*f[k|j|p];
                    g[i|j]   = l + r;
                    g[i|j|M] = l - r;
                }
            }
            swap(f,g);
        }
    }
    template<int prime=mod> inline vector<ModInt<prime>> convolution_friendrymod(const vector<Mint>& a,const vector<Mint>& b){
        if (min(a.size(), b.size()) <= 60) {
            vector<ModInt<prime>> f(a.size() + b.size() - 1);
            for (int i = 0; i < a.size(); i++) for (int j = 0; j < b.size(); j++) f[i+j]+=a[i].x*b[j].x;
            return f;
        }
        int N,M=a.size()+b.size()-1; for(N=1;N<M;N*=2);
        ModInt<prime> inverse(N); inverse = inverse.inv();
        vector<ModInt<prime>> g(N,0),h(N,0);
        for(int i=0;i<a.size();++i) g[i]=a[i].x;
        for(int i=0;i<b.size();++i) h[i]=b[i].x;
        ntt<prime>(g); ntt<prime>(h);
        for(int i = 0; i < N; ++i) g[i] *= h[i]*inverse;
        reverse(g.begin()+1,g.end());
        ntt<prime>(g);
        return g;
    }
    inline vector<Mint> convolution_arbitrarymod(const vector<Mint>& g,const vector<Mint>& h){
        auto f1 = convolution_friendrymod<prime1>(g, h);
        auto f2 = convolution_friendrymod<prime2>(g, h);
        auto f3 = convolution_friendrymod<prime3>(g, h);
        vector<Mint> f(f1.size());
        for(int i=0; i<f1.size(); ++i) f[i] = garner(f1[i],f2[i],f3[i]);
        return f;
    }
    inline vector<ModInt<998244353>> convolution(const vector<ModInt<998244353>>& g,const vector<ModInt<998244353>>& h){return convolution_friendrymod<998244353>(g,h);}
    inline vector<ModInt<1000000007>> convolution(const vector<ModInt<1000000007>>& g,const vector<ModInt<1000000007>>& h){return convolution_arbitrarymod(g,h);}
    static inline Mint nth_term_impl(long long n, Fps numerator,Fps denominator) {
        while(n) {
            numerator   *= denominator.minus_x();
            numerator    = ((n&1)?numerator.odd():numerator.even());
            denominator *= denominator.minus_x();
            denominator  = denominator.even();
            n >>= 1;
        }
        return numerator[0];
    }
public:
    //a0 + a_1*x^1 + a_2*x^2 + ... + a_(n-1)*x^(n-1)
    inline static Mint nth_term(long long n,const Fps& numerator,const Fps& denominator) {return nth_term_impl(n,numerator,denominator);}
    FormalPowerSeries(vector<Mint> v){*this=FormalPowerSeries(v.size());for(int i=0;i<v.size();++i) (*this)[i]=v[i];}
    Fps operator*(const Fps& r) const { return Fps(*this) *= r; }
    Fps &operator*=(const Fps& r) {return *this = convolution(*this,r);}
    Fps operator*(const int r) const {return Fps(*this) *= r; }
    Fps &operator*=(const int r) {for(int i=0;i< this->size(); ++i) (*this)[i] *= r; return *this; }
    Fps operator*(const long long int r) const {return Fps(*this) *= r; }
    Fps &operator*=(const long long int r) {for(int i=0;i< this->size(); ++i) (*this)[i] *= r; return *this; }
    Fps operator*(const Mint r) const {return Fps(*this) *= r; }
    Fps &operator*=(const Mint r) {for(int i=0;i< this->size(); ++i) (*this)[i] *= r; return *this; }
    Fps operator/(const int r) const {return Fps(*this) /= r; }
    Fps &operator/=(const int r) {return (*this) *= Mint(r).inv(); }
    Fps operator+(const Fps& r) const { return Fps(*this) += r; }
    Fps &operator+=(const Fps& r) {if(r.size() > this->size()) this->resize(r.size());for(int i = 0; i < r.size(); i++) (*this)[i] += r[i];return *this;}
    Fps operator+(const int r) const {return Fps(*this) += r; }
    Fps &operator+=(const int r) {for(int i=0;i< this->size(); ++i) (*this)[i] += r; return *this; }
    Fps operator-(void) const {return Fps(*this) *= (-1);}
    Fps operator-(const Fps& r) const { return Fps(*this) -= r; }
    Fps &operator-=(const Fps& r) {if(r.size() > this->size()) this->resize(r.size());for(int i = 0; i < r.size(); i++) (*this)[i] -= r[i];return *this;}
    Fps operator-(const int r) const {return Fps(*this) -= r; }
    Fps &operator-=(const int r) {for(int i=0;i< this->size(); ++i) (*this)[i] -= r; return *this; }
    Fps prefix(size_t n) const {return Fps(this->begin(),this->begin()+min(n,this->size()));}
    Fps pow(long long k,size_t n) const {
        Fps ret(n,0);
        for(size_t i=0; i < min(n,this->size()) && i*k < n; ++i) {
            if((*this)[i].x == 0) continue;
            Mint t0=(*this)[i], t0_inv=t0.inv();
            Fps tmp(n-i);for(int j=i;j<min(n,this->size()); ++j) tmp[j-i]=(*this)[j]*t0_inv;
            tmp = (tmp.log(n)*k).exp(n)*(t0.pow(k));
            for(int j=0;j+i*k<n;++j) ret[j+i*k] = tmp[j];
            break;
        }
        return ret;
    }
    Fps pow(long long k) const {return pow(k,this->size());}
    Fps inv(size_t n) const {Fps ret({Mint(1)/(*this)[0]});for(size_t i=1;i < n; i<<=1) ret = (ret*2-ret*(ret*(this->prefix(i<<1))).prefix(i<<1)).prefix(i<<1);return ret.prefix(n);}
    Fps inv(void) const {return inv(this->size());}
    Fps diff(void) const {Fps ret(max(0,int(this->size())-1));for(int i=0;i<ret.size(); ++i) ret[i]=(*this)[i+1]*(i+1);return ret;}
    Fps intg(void) const {Fps ret(this->size()+1);for(int i=1;i<ret.size(); ++i) ret[i]=(*this)[i-1]/i;return ret;}
    Fps log(size_t n) const {return (this->diff()*this->inv(n)).intg().prefix(n);}
    Fps log(void) const {return log(this->size());}
    Fps exp(size_t n) const {Fps ret(1,1);for(size_t i=1;i<n;i<<=1) ret = (ret*(this->prefix(i<<1) + Fps(1,1) - ret.log(i<<1))).prefix(i<<1);return ret.prefix(n);}
    Fps exp(void) const {return exp(this->size());}
    friend ostream &operator<<(ostream &os, const Fps& fps) {os << "{" << fps[0];for(int i=1;i<fps.size();++i) os << ", " << fps[i];return os << "}";}
};

using fps = FormalPowerSeries<MOD2>;

/*
 * @title CombinationMod - mod上の二項係数・階乗
 * @docs md/math/CombinationMod.md
 */
template<long long mod> class CombinationMod {
	vector<long long> fac,finv,inv;
public:
	CombinationMod(int N) : fac(N + 1), finv(N + 1), inv(N + 1) {
		fac[0] = fac[1] = finv[0] = finv[1] = inv[1] = 1;
		for (int i = 2; i <= N; ++i) {
			fac[i] = fac[i - 1] * i % mod;
			inv[i] = mod - inv[mod%i] * (mod / i) % mod;
			finv[i] = finv[i - 1] * inv[i] % mod;
		}
	}
	inline long long binom(int n, int k) {
		return ((n < 0 || k < 0 || n < k) ? 0 : fac[n] * (finv[k] * finv[n - k] % mod) % mod);
	}
	inline long long factorial(int n) {
		return fac[n];
	}
};

int main() {
    cin.tie(0);ios::sync_with_stdio(false);
    int N; cin >> N;

    int M = 100000;
    vector<int> cnt(M+1,0);
    for(int i=0;i<2*N;++i) {
        int h; cin >> h; cnt[h]++;
    }

    vector<modint> fact_odd(2*N,0);
    fact_odd[1]=1;
    for(int i=3; i<2*N;i+=2) fact_odd[i] = fact_odd[i-2]*i;

    CombinationMod<MOD2> CM(2*N);

    vector<fps> vf;
    priority_queue_reverse<pair<int,int>> pq;
    for(int i=1; i<= M; ++i) {
        if(!cnt[i]) continue;
        int n = cnt[i];
        int m = n/2;
        fps f(m+1,0);
        f[0]=1;
        for(int j=1;j<=m;++j) {
            // n人から2j人選ぶ-> n_C_2j
            // 2j人からjペア作る-> (2j-1)*(2j-3)*...*3*1;
            f[j] = fact_odd[2*j-1]*CM.binom(n,2*j);
        }
        vf.push_back(f);
        pq.push({f.size(),vf.size()-1});
    }
    while(pq.size()>=2) {
        auto l = pq.top().second; pq.pop();
        auto r = pq.top().second; pq.pop();
        auto f = vf[l]*vf[r];
        vf.push_back(f);
        pq.push({f.size(),vf.size()-1});
    }
    modint ans = 0;
    {
        // auto c = pq.top().second; pq.pop();
        // auto f = vf[c];
        // for(int i=0;i<f.size();++i) f[i] *= fact_odd[2*(N-i)-1];
        // for(int i=0;i<f.size();++i) ans += f[i]*(1 - 2*(i%2));
    }
    cout << ans << endl;
    return 0;
}
