/**
 *    author:  otera    
**/
#include<iostream>
#include<string> 
#include<cstdio>
#include<cstring>
#include<vector>
#include<cmath>
#include<algorithm> 
#include<functional>
#include<iomanip>
#include<queue>
#include<deque>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<unordered_set>
#include<utility>
#include<cassert>
#include<atcoder/all>
using namespace std;
// using namespace atcoder;

// #define int long long
typedef long long ll;
typedef unsigned long long ul;
typedef unsigned int ui;
typedef long double ld;
const int inf=1e9+7;
const ll INF=1LL<<60 ;
const ll mod=1e9+7 ;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef complex<ld> Point;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<int, int> P;
typedef pair<ld, ld> LDP;
typedef pair<ll, ll> LP;
#define fr first
#define sc second
#define all(c) c.begin(),c.end()
#define pb push_back
#define debug(x)  cerr << #x << " = " << (x) << endl;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

#define MOD 998244353LL

namespace ac = atcoder;

int cnt[100100];
ll fact[100100], inv[100100], finv[100100];
ll dfact[100100];

ll com(ll n, ll k) {
    if (n < k || n < 0 || k < 0) return 0;
    return (fact[n] * finv[k] % MOD) * finv[n - k] % MOD;
}

void solve() {
    inv[1] = 1;
    for(int i = 2; i < 100100; ++ i) {
        inv[i] = (MOD - MOD / i) * inv[MOD % i] % MOD;
    }
    fact[0] = finv[0] = 1;
    for(int i = 1; i < 100100; ++ i) {
        fact[i] = fact[i - 1] * i % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
    dfact[0] = dfact[1] = 1;
    for(int i = 2; i < 100100; ++ i) {
        dfact[i] = dfact[i - 2] * i % MOD;
    }
	int n; cin >> n;
    rep(i, 2 * n) {
        int h; cin >> h;
        cnt[h] ++;
    }
    queue<vector<ll>> que;
    rep(i, 100100) {
        if(cnt[i] > 0) {
            int m = cnt[i];
            // cerr << m << endl;
            vector<ll> v(m / 2 + 1);
            v[0] = 1;
            rep1(j, m / 2) {
                v[j] = com(m, 2 * j) * dfact[2 * j - 1] % MOD;
            }
            que.push(v);
        }
    }
    queue<vector<ll>> que2;
    while(que.size() >= 2) {
        vector<ll> a = que.front(); que.pop();
        vector<ll> b = que.front(); que.pop();
        vector<ll> c = ac::convolution<998244353>(a, b);
        que2.push(c);
        if(que.size() <= 1) {
            if(que.size() == 1) que2.push(que.front()), que.pop();
            swap(que2, que);
        }
    }
    vector<ll> c = que.front();
    // cerr << c[0] << " " << c[1] << " " << c[2] << endl;
    ll ans = 0;
    for(int i = 0; i <= min(n - 1, (int)c.size() - 1); ++ i) {
        if(i % 2 == 0) (ans += c[i] * dfact[2 * n - 2 * i - 1]) %= MOD;
        else (ans += MOD - c[i] * dfact[2 * n - 2 * i - 1]) %= MOD;
    }
    if(c.size() == n + 1) {
        if(n % 2 == 0) (ans += c[n]) %= MOD;
        else (ans += MOD - c[n]) %= MOD;
    }
    cout << ans % MOD << endl;
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	//cout << fixed << setprecision(10);
	//int t; cin >> t; rep(i, t)solve();
	solve();
    return 0;
}