#include <bits/stdc++.h>
using namespace std;
//using namespace atcoder;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin);i<(end);i++)
#define REP(i, n) FOR(i,0,n)
#define IFOR(i, begin, end) for(int i=(end)-1;i>=(begin);i--)
#define IREP(i, n) IFOR(i,0,n)
#define Sort(v) sort(v.begin(), v.end())
#define Reverse(v) reverse(v.begin(), v.end())
#define all(v) v.begin(),v.end()
#define SZ(v) ((int)v.size())
#define Lower_bound(v, x) distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x) distance(v.begin(), upper_bound(v.begin(), v.end(), x))
#define chmax(a, b) a = max(a, b)
#define chmin(a, b) a = min(a, b)
#define bit(n) (1LL<<(n))
#define debug(x) cout << #x << "=" << x << endl;
#define vdebug(v) { cout << #v << "=" << endl; REP(i_debug, v.size()){ cout << v[i_debug] << ","; } cout << endl; }
#define mdebug(m) { cout << #m << "=" << endl; REP(i_debug, m.size()){ REP(j_debug, m[i_debug].size()){ cout << m[i_debug][j_debug] << ","; } cout << endl;} }
#define pb push_back
#define fi first
#define se second
#define int long long
#define INF 1000000000000000000
template<typename T> istream &operator>>(istream &is, vector<T> &v){ for (auto &x : v) is >> x; return is; }
template<typename T> ostream &operator<<(ostream &os, vector<T> &v){ for(int i = 0; i < v.size(); i++) { cout << v[i]; if(i != v.size() - 1) cout << endl; }; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, pair<T1, T2> p){ cout << '(' << p.first << ',' << p.second << ')'; return os; }
template<typename T> void Out(T x) { cout << x << endl; }
template<typename T1, typename T2> void chOut(bool f, T1 y, T2 n) { if(f) Out(y); else Out(n); }

using vec = vector<int>;
using mat = vector<vec>;
using Pii = pair<int, int>;
using v_bool = vector<bool>;
using v_Pii = vector<Pii>;

//int dx[4] = {1,0,-1,0};
//int dy[4] = {0,1,0,-1};
//char d[4] = {'D','R','U','L'};

//const int mod = 1000000007;
const int mod = 998244353;

template<long long MOD>
struct ModInt{

    using ll = long long;
    ll val;

    void setval(ll v) { val = v % MOD; };
    ModInt(): val(0) {}
    ModInt(ll v) { setval(v); };

    ModInt operator+(const ModInt &x) const { return ModInt(val + x.val); }
    ModInt operator-(const ModInt &x) const { return ModInt(val - x.val + MOD); }
    ModInt operator*(const ModInt &x) const { return ModInt(val * x.val); }
    ModInt operator/(const ModInt &x) const { return *this * x.inv(); }
    ModInt operator-() const { return ModInt(MOD - val); }
    ModInt operator+=(const ModInt &x) { return *this = *this + x; }
    ModInt operator-=(const ModInt &x) { return *this = *this - x; }
    ModInt operator*=(const ModInt &x) { return *this = *this * x; }
    ModInt operator/=(const ModInt &x) { return *this = *this / x; }
    bool operator==(const ModInt &x) const { return (*this).val == x.val; }

    friend ostream& operator<<(ostream &os, const ModInt &x) { os << x.val; return os; }
    friend istream& operator>>(istream &is, ModInt &x) { is >> x.val; x.val = (x.val % MOD + MOD) % MOD; return is; }

    ModInt pow(ll n) const {
        ModInt a = 1;
        if(n == 0) return a;
        int i0 = 64 - __builtin_clzll(n);
        for(int i = i0 - 1; i >= 0; i--){
            a = a * a;
            if((n >> i) & 1) a *= (*this); 
        }
        return a;
    }
    ModInt inv() const { return this->pow(MOD - 2); }
};

using mint = ModInt<mod>; mint pow(mint x, long long n) { return x.pow(n); }
//using mint = double; //for debug
using mvec = vector<mint>;
using mmat = vector<mvec>;

struct Combination{

    vector<mint> fact, invfact;

    Combination(int N){
        fact = vector<mint>({mint(1)});
        invfact = vector<mint>({mint(1)});
        fact_initialize(N);
    }

    void fact_initialize(int N){
        int i0 = fact.size();
        if(i0 >= N + 1) return;
        fact.resize(N + 1);
        invfact.resize(N + 1);
        for(int i = i0; i <= N; i++) fact[i] = fact[i - 1] * i;
        invfact[N] = (mint)1 / fact[N];
        for(int i = N - 1; i >= i0; i--) invfact[i] = invfact[i + 1] * (i + 1); 
    }

    mint nCr(int n, int r){
        if(n < 0 || r < 0 || r > n) return mint(0);
        if(fact.size() < n + 1) fact_initialize(n);
        return fact[n] * invfact[r] * invfact[n - r];
    }

    mint nPr(int n, int r){
        if(n < 0 || r < 0 || r > n) return mint(0);
        if(fact.size() < n + 1) fact_initialize(n);
        return fact[n] * invfact[n - r];
    }

    mint Catalan(int n){
        if(n < 0) return 0;
        else if(n == 0) return 1;
        if(fact.size() < 2 * n + 1) fact_initialize(2 * n);
        return fact[2 * n] * invfact[n + 1] * invfact[n];
    }

};

template<long long MOD>
class NTT
{
private:
    vector<ModInt<MOD>> f, f_tmp;

    void init(){
        n = 31 - __builtin_clz((signed)N);
        assert(N == (1 << n));

        assert((e.pow(N)).val == 1);
        pow_e.resize(N + 1);
        pow_e[0] = 1;
        bool e_valid = true;
        FOR(i, 1, N){
            pow_e[i] = pow_e[i - 1] * e;
            if(pow_e[i].val == 1) e_valid = false;
        }
        pow_e[N] = 1;
        assert(e_valid);

        inv_N = ((ModInt<MOD>)N).inv();

        f.resize(N);
        f_tmp.resize(N);
    }

    void forward_exec(int l, int r, int t){
        if(t == n) return;
        int sz = (r - l) >> 1;
        REP(i, sz){
            f_tmp[l + i] = f[l + 2 * i];
            f_tmp[l + sz + i] = f[l + 2 * i + 1];
        }
        FOR(i, l, r) f[i] = f_tmp[i];
        forward_exec(l, l + sz, t + 1);
        forward_exec(l + sz, r, t + 1);

        REP(i, sz) f_tmp[l + i] = f[l + i] + f[l + sz + i] * pow_e[i << t];
        REP(i, sz) f_tmp[l + sz + i] = f[l + i] + f[l + sz + i] * pow_e[(sz + i) << t];
        FOR(i, l, r) f[i] = f_tmp[i];
    }

    void inverse_exec(int l, int r, int t){
        if(t == n) return;
        int sz = (r - l) / 2;
        REP(i, sz){
            f_tmp[l + i] = f[l + 2 * i];
            f_tmp[l + sz + i] = f[l + 2 * i + 1];
        }
        FOR(i, l, r) f[i] = f_tmp[i];
        inverse_exec(l, l + sz, t + 1);
        inverse_exec(l + sz, r, t + 1);

        REP(i, sz) f_tmp[l + i] = f[l + i] + f[l + sz + i] * pow_e[N - (i << t)];
        REP(i, sz) f_tmp[l + sz + i] = f[l + i] + f[l + sz + i] * pow_e[N - ((sz + i) << t)];
        FOR(i, l, r) f[i] = f_tmp[i];
    }

public:

    int N, n;
    ModInt<MOD> e, inv_N;
    vector<ModInt<MOD>> pow_e;

    //array size M is converted to N = 2^n (>=M)
    //only for MOD = 924844033, 998244353, 1012924417
    NTT(int M){
        N = 1;
        while(M > N) N <<= 1;

        ModInt<MOD> x;
        if(MOD == 924844033) x = 5;
        else if(MOD == 998244353) x = 3;
        else if(MOD == 1012924417) x = 5;
        else assert(false);
        
        assert((MOD - 1) % N == 0);
        e = x.pow((MOD - 1) / N);

        init();
    }

    //N=2^n, e^N=1, e^k!=1 (k<N) must be satisfied
    NTT(int N, ModInt<MOD> e): N(N), e(e){
        init();
    }

    void exec(vector<ModInt<MOD>> &F, bool inverse = false){
        assert(F.size() == N);
        f.swap(F);
        if(!inverse) forward_exec(0, N, 0);
        else inverse_exec(0, N, 0);
        F.swap(f);
        if(inverse){
            REP(i, N) F[i] *= inv_N;
        }
    }

    //if resize_result is true, the array size of the result becomes A.size() + B.size() - 1
    //array size must be equal to N if negetive indices are included
    vector<ModInt<MOD>> convolution(vector<ModInt<MOD>> A, vector<ModInt<MOD>> B, bool resize_result = false){
        int sA = A.size(), sB = B.size();
        assert(sA <= N && sB <= N);
        A.resize(N);
        B.resize(N);   
        exec(A);
        exec(B);

        vector<ModInt<MOD>> C(N);
        REP(i, N) C[i] = A[i] * B[i];
        exec(C, true);

        if(resize_result) C.resize(sA + sB - 1);

        return C;
    }
};

signed main(){

    int N; cin >> N;
    vec h(2 * N); cin >> h;
    const int M = 100000;
    vec cnt(M);
    REP(i, 2 * N) cnt[h[i] - 1]++;

    Combination C(M);
    mvec G(M + 1);
    G[0] = 1;
    FOR(i, 2, M + 1) if(i % 2 == 0) G[i] = G[i - 2] * (i - 1);

    mmat S;
    priority_queue<Pii, vector<Pii>, greater<Pii>> que;
    int id = 0;
    REP(i, M) if(cnt[i] >= 2){
        mvec tmp(cnt[i] / 2 + 1);
        REP(n, cnt[i] / 2 + 1) tmp[n] = C.nCr(cnt[i], 2 * n) * G[2 * n]; 
        S.pb(tmp);
        que.push(Pii(SZ(tmp), id));
        id++;
    }

    while(que.size() >= 2){
        Pii p1 = que.top(); que.pop();
        Pii p2 = que.top(); que.pop();
        NTT<mod> ntt(p1.fi + p2.fi - 1);
        mvec tmp = ntt.convolution(S[p1.se], S[p2.se], true);
        S.pb(tmp);
        que.push(Pii(SZ(tmp), id));
        id++;
    }
    
    mint ans = 0;
    if(SZ(S)){
        mvec num = S.back();
        REP(i, SZ(num)){
            if(i % 2 == 0) ans += G[2 * (N - i)] * num[i];
            else ans -= G[2 * (N - i)] * num[i];
        }
    }else{
        ans = G[2 * N];
    }
    Out(ans);

    return 0;
}


Measured memory_bytes: 17124