#line 2 "header.hpp"

//%snippet.set('header')%
//%snippet.fold()%
#ifndef HEADER_H
#define HEADER_H

// template version 2.0
using namespace std;
#include <bits/stdc++.h>

// varibable settings
const long long INF = 1e18;
template <class T> constexpr T inf = numeric_limits<T>::max() / 2.1;

#define _overload3(_1, _2, _3, name, ...) name
#define _rep(i, n) repi(i, 0, n)
#define repi(i, a, b) for (ll i = (ll)(a); i < (ll)(b); ++i)
#define rep(...) _overload3(__VA_ARGS__, repi, _rep, )(__VA_ARGS__)
#define _rrep(i, n) rrepi(i, 0, n)
#define rrepi(i, a, b) for (ll i = (ll)((b)-1); i >= (ll)(a); --i)
#define r_rep(...) _overload3(__VA_ARGS__, rrepi, _rrep, )(__VA_ARGS__)
#define each(i, a) for (auto &&i : a)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define pb(a) push_back(a)
#define mp(a, b) make_pair(a, b)
#define mt(...) make_tuple(__VA_ARGS__)
#define ub upper_bound
#define lb lower_bound
#define lpos(A, x) (lower_bound(all(A), x) - A.begin())
#define upos(A, x) (upper_bound(all(A), x) - A.begin())
template <class T, class U> inline void chmax(T &a, const U &b) { if ((a) < (b)) (a) = (b); }
template <class T, class U> inline void chmin(T &a, const U &b) { if ((a) > (b)) (a) = (b); }
template <typename X, typename T> auto make_table(X x, T a) { return vector<T>(x, a); }
template <typename X, typename Y, typename Z, typename... Zs> auto make_table(X x, Y y, Z z, Zs... zs) { auto cont = make_table(y, z, zs...); return vector<decltype(cont)>(x, cont); }

#define cdiv(a, b) (((a) + (b)-1) / (b))
#define is_in(x, a, b) ((a) <= (x) && (x) < (b))
#define uni(x) sort(all(x)); x.erase(unique(all(x)), x.end())
#define slice(l, r) substr(l, r - l)

typedef long long ll;
typedef long double ld;
using vl = vector<ll>;
using vvl = vector<vl>;
using pll = pair<ll, ll>;

template <typename T>
using PQ = priority_queue<T, vector<T>, greater<T>>;
void check_input() { assert(cin.eof() == 0); int tmp; cin >> tmp; assert(cin.eof() == 1); }

#if defined(PCM) || defined(LOCAL)
#else
#define dump(...) ;
#define dump_1d(...) ;
#define dump_2d(...) ;
#define cerrendl ;
#endif

#endif /* HEADER_H */
//%snippet.end()%
#line 2 "solve.cpp"
template<class T=ll> using vec = vector<T>;
struct Fast { Fast() { std::cin.tie(0); ios::sync_with_stdio(false); } } fast;

// {{{ include acl-library
// #include <atcoder/fenwicktree>
// #include <atcoder/segtree>
// #include <atcoder/lazysegtree>
// #include <atcoder/string>
// #include <atcoder/math>
#include <atcoder/convolution>
// #include <atcoder/modint>
// #include <atcoder/dsu>
// #include <atcoder/maxflow>
// #include <atcoder/mincostflow>
// #include <atcoder/scc>
// #include <atcoder/twosat>
using namespace atcoder;
// }}}

int mod = 998244353;
struct mint {  //{{{
    ll x;
    mint(ll x = 0) : x((x % mod + mod) % mod) {}

    // ?= operator
    mint& operator+=(const mint a) {
        (x += a.x) %= mod;
        return *this;
    }
    mint& operator-=(const mint a) {
        (x += mod - a.x) %= mod;
        return *this;
    }
    mint& operator*=(const mint a) {
        (x *= a.x) %= mod;
        return *this;
    }
    mint& operator/=(const mint& rhs) {
        if (rhs.x == 0) throw runtime_error("mint zero division");
        return *this *= rhs.inv();
    }

    mint operator+(const mint a) const {
        mint res(*this);
        return res += a;
    }
    mint operator-(const mint a) const {
        mint res(*this);
        return res -= a;
    }
    mint operator*(const mint a) const {
        mint res(*this);
        return res *= a;
    }
    mint operator/(const mint a) const {
        mint res(*this);
        return res /= a;
    }

    mint pow(ll n) const {
        mint res(1), x(*this);
        if (n < 0) {
            n = -n;
            x = (*this).inv();
        }
        while (n) {
            if (n & 1) res *= x;
            x *= x;
            n >>= 1;
        }
        return res;
    }

    mint inv() const {
        if (x == 0) throw runtime_error("inv does not exist");
        return pow(mod - 2);
    }
    // mint inv()const{
    //     int x,y;
    //     int g=extgcd(v,mod,x,y);
    //     assert(g==1);
    //     if(x<0)x+=mod;
    //     return mint(x);
    // }

    bool operator<(const mint& r) const { return x < r.x; }
    bool operator==(const mint& r) const { return x == r.x; }
};
istream& operator>>(istream& is, const mint& a) { return is >> a.x; }
ostream& operator<<(ostream& os, const mint& a) { return os << a.x; }
//}}}

struct combination {  // {{{
    vector<mint> fact, ifact;
    combination(int n) : fact(n + 1), ifact(n + 1) {
        assert(n < mod);
        fact[0] = 1;
        for (int i = 1; i <= n; ++i) fact[i] = fact[i - 1] * i;
        ifact[n] = fact[n].inv();
        for (int i = n; i >= 1; --i) ifact[i - 1] = ifact[i] * i;
    }
    mint operator()(int n, int k) {
        if (k < 0 || k > n) return 0;
        return fact[n] * ifact[k] * ifact[n - k];
    }
}  // }}}
com(500001);  // check this is enough

int solve() {
    ll n;cin>>n;/*{{{*/
    vl h(2*n);
    map<int, int> cnt;
    rep(i, 2*n){
        cin>>h[i];
        cnt[h[i]]++;
    }
    vec<int> y;
    for (auto [key, c] : cnt) { y.pb(c); }
    dump(y);/*}}}*/

    vec<mint> q(2*n);  // q[i] : i!!{{{
    q[1] = 1;
    for(ll i=3; i<2*n; i+=2){
        q[i] = q[i-2] * i;
    }
    dump(q);/*}}}*/

    auto f = [&](auto& z) -> vec<int> {/*{{{*/
        vec<int> res = {1};
        rep(p, 1, z/2 + 1){
            res.pb((com(z, p*2) * q[2*p-1]).x);
        }
        return res;
    };/*}}}*/

    deque<vec<int>> dq;
    rep(i, sz(y)){
        dq.push_back(f(y[i]));
        dump(y[i], f(y[i]));
    }
    while(sz(dq)>1){
        auto u = dq.front(); dq.pop_front();
        auto v = dq.front(); dq.pop_front();
        dq.push_back(convolution(u, v));
    }
    auto cntk = dq.front();  // cntk[p] : kペア選ぶ方法
    dump(cntk);

    mint ans = 0;
    rep(p, sz(cntk)){
        ans += mint(cntk[p]) * pow(-1, p) * (n>p ? q[2*n-2*p-1]: 1);
        dump(p, ans);
    }
    cout << ans << endl;

    return 0; 
}


int main(){/*{{{*/
    solve();
    check_input();
    return 0;
}/*}}}*/


Measured memory_bytes: 23372