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

#include <atcoder/all>
using namespace atcoder;

#define rep(i, m, n) for(int(i) = (int)(m); i < (int)(n); ++i)
#define rep2(i, m, n) for(int(i) = (int)(n)-1; i >= (int)(m); --i)
#define REP(i, n) rep(i, 0, n)
#define REP2(i, n) rep2(i, 0, n)
#define all(hoge) (hoge).begin(), (hoge).end()
#define en '\n'
using ll = long long;
using ull = unsigned long long;
template <class T>
using vec = vector<T>;
template <class T>
using vvec = vector<vec<T>>;
typedef pair<ll, ll> P;
using tp = tuple<ll, ll, ll>;
constexpr long long INF = 1LL << 60;
constexpr int INF_INT = 1 << 25;
//constexpr long long MOD = (ll)1e9 + 7;
constexpr long long MOD = 998244353LL;
using ld = long double;
static const ld pi = 3.141592653589793L;
typedef vector<ll> Array;
typedef vector<Array> Matrix;

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

//グラフ関連
struct Edge {
    ll to, cap, rev;
    Edge(ll _to, ll _cap, ll _rev) {
        to = _to;
        cap = _cap;
        rev = _rev;
    }
};
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;

void add_edge(Graph &G, ll from, ll to, ll cap, bool revFlag, ll revCap) {
    G[from].push_back(Edge(to, cap, (ll)G[to].size()));
    if(revFlag)
        G[to].push_back(Edge(from, revCap, (ll)G[from].size() - 1));
}

template <int mod>
struct ModInt {
    int x;

    ModInt() : x(0) {}

    ModInt(int64_t 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 ModInt &p) {
        if((x += mod - p.x) >= mod)
            x -= mod;
        return *this;
    }

    ModInt &operator*=(const ModInt &p) {
        x = (int)(1LL * x * p.x % mod);
        return *this;
    }

    ModInt &operator/=(const ModInt &p) {
        *this *= p.inverse();
        return *this;
    }

    ModInt operator-() const { return ModInt(-x); }

    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 inverse() 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(int64_t n) const {
        ModInt ret(1), mul(x);
        while(n > 0) {
            if(n & 1)
                ret *= mul;
            mul *= mul;
            n >>= 1;
        }
        return ret;
    }

    friend ostream &operator<<(ostream &os, const ModInt &p) {
        return os << p.x;
    }

    friend istream &operator>>(istream &is, ModInt &a) {
        int64_t t;
        is >> t;
        a = ModInt<mod>(t);
        return (is);
    }

    static int get_mod() { return mod; }
};

using mint = ModInt<MOD>;

// 二項係数ライブラリ
template <class T>
struct Combination {
    vector<T> fact_, inv_, finv_;
    constexpr Combination() {}
    constexpr Combination(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) {
        init(n + 1);
    }
    constexpr void init(int n) noexcept {
        fact_.assign(n, 1), inv_.assign(n, 1), finv_.assign(n, 1);
        int MOD = fact_[0].get_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 nPr(int n, int k) const noexcept {
        if(n < k || n < 0 || k < 0)
            return 0;
        return fact_[n] * finv_[n - k];
    }
    constexpr T nCr(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 nHr(int n, int k) const noexcept {
        if(n < k || n < 0 || k < 0)
            return 0;
        return nCr(n + k - 1, k);
    }
    constexpr T fact(int n) const noexcept {
        if(n < 0)
            return 0;
        return fact_[n]; //n!
    }
    constexpr T inv(int n) const noexcept {
        if(n < 0)
            return 0;
        return inv_[n]; //1/n
    }
    constexpr T finv(int n) const noexcept {
        if(n < 0)
            return 0;
        return finv_[n]; //1/n!
    }
};

void solve() {
    ll n;
    cin >> n;
    map<ll, ll> mp;
    REP(i, 2 * n) {
        ll h;
        cin >> h;
        mp[h]++;
    }

    using S = pair<ll, vec<ll>>; //size,d[i]:各グループ内でi個ペアを含む場合の数
    priority_queue<S, vec<S>, greater<S>> que;
    for(auto i : mp) {
        ll v = i.second;
        vec<ll> d;
        ll con = 1;
        d.push_back(con);
        while(v >= 2) {
            con *= v * (v - 1) / 2 % MOD;
            con %= MOD;
            d.push_back(con);
            v -= 2;
        }
        que.push({i.second / 2 + 1, d});
    }

    while(que.size() > 1) {
        //sizeが小さい方からマージする
        auto [sa, a] = que.top();
        que.pop();
        auto [sb, b] = que.top();
        que.pop();
        auto c = convolution(a, b);
        que.push({sa + sb - 1, c});
    }

    Combination<mint> com(2 * n);

    auto [m, p] = que.top();

    mint ans = 0;
    REP(i, m) {
        mint tmp = com.nCr(2 * n - 2 * i, n - i) * com.fact(n - i) / mint(2).pow(n - i) * p[i];
        if(i % 2) {
            ans -= tmp;
        } else {
            ans += tmp;
        }
    }
    cout << ans << en;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    /*
    ll t;
    cin >> t;
    while(t--)*/
    solve();

    return 0;
}
