#ifdef LOCAL
#define _GLIBCXX_DEBUG
#endif
#include<bits/stdc++.h>
#include<atcoder/all>
using namespace atcoder;
using namespace std;
#define rep(i,s,t) for(ll i = (ll)(s); i < (ll)(t); i++)
#define rrep(i,s,t) for(ll i = (ll)(s-1);(ll)(t) <= i; i--)
#define all(x) (x).begin(), (x).end()
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> Pll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
constexpr ll INF = numeric_limits<ll>::max()/4;
constexpr ll n_max = 2e5+10;
#define int ll
const long double pi = 3.14159265358979323846;

using mint = modint998244353;
string to_string(mint &m){
    return to_string(m.val());
}

string to_string(vector<mint> &v){
    string res = "{";
    ll n = v.size();
    rep(i, 0, n) {
        res += to_string(v[i]);
        if (i == n - 1) res += "}";
        else
            res += " ";
    }
    return res;
}

template <typename A, typename B>
string to_string(pair<A, B> p);
string to_string(const string &s) {return '"' + s + '"';}
string to_string(const char *c) {return to_string((string) c);}
string to_string(bool b) {return (b ? "true" : "false");}
template <size_t N>
string to_string(bitset<N> v){
    string res = "";
    for(size_t i = 0; i < N; i++) res += static_cast<char>('0' + v[i]);
    return res;
}
template <typename A>
string to_string(A v) {
    bool first = true;
    string res = "{";
    for(const auto &x : v) {
        if(!first) res += ", ";
        first = false;
        res += to_string(x);
    }
    res += "}";
    return res;
}
template <typename A, typename B>
string to_string(pair<A, B> p){return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";}

void debug_out() {cerr << endl;}
template<typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << " " << to_string(H);
    debug_out(T...);
}

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

template<class T>
bool chmax(T &a, T b){if(a < b){a = b; return true;} return false;}
template<class T>
bool chmin(T &a, T b){if(a > b){a = b; return true;} return false;}


template<class T> struct BiCoef {
    vector<T> fact_, inv_, finv_;
    constexpr BiCoef() {}
    constexpr BiCoef(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) {
        init(n);
    }
    constexpr void init(int n) noexcept {
        fact_.assign(n, 1), inv_.assign(n, 1), finv_.assign(n, 1);
        int MOD = fact_[0].mod();
        for(int i = 2; i < n; i++){
            fact_[i] = fact_[i-1] * i;
            inv_[i] = -inv_[MOD%i] * (MOD/i);
            finv_[i] = finv_[i-1] * inv_[i];
        }
    }
    constexpr T com(int n, int k) const noexcept {
        if (n < k || n < 0 || k < 0) return 0;
        return fact_[n] * finv_[k] * finv_[n-k];
    }
    constexpr T fact(int n) const noexcept {
        if (n < 0) return 0;
        return fact_[n];
    }
    constexpr T inv(int n) const noexcept {
        if (n < 0) return 0;
        return inv_[n];
    }
    constexpr T finv(int n) const noexcept {
        if (n < 0) return 0;
        return finv_[n];
    }
};

BiCoef<mint> bc(n_max);

signed main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    ll n; cin >> n;
    vector<ll> cnt(n_max);
    rep(i,0,n * 2){
        ll h; cin >> h;
        cnt[h]++;
    }
   
    vector<mint> G(n_max);
    G[0] = 1;
    rep(i, 1, n_max) G[i] = G[i - 1] * (2 * i - 1);
    queue<vector<mint>> que;
    rep(i,0,n_max){
        if(cnt[i]){
            vector<mint> t;
            for (int j = 0; j <= cnt[i]; j += 2){
                t.emplace_back(bc.com(cnt[i], j) * G[j / 2]);
            }
            que.emplace(t);
        }
    }

    while(que.size() > 1){
        auto a = que.front();
        que.pop();
        auto b = que.front();
        que.pop();
        auto c = convolution(a, b);
        que.emplace(c);
        debug(a, b, c);
    }

    auto c = que.front();
    mint ans = 0;
    rep(i,0,c.size()){
        if(~i & 1)ans += c[i] * G[n - i];
        else
            ans -= c[i] * G[n - i];
    }
    debug(c);
    cout << ans.val() << "\n";
}

Measured memory_bytes: 13468