#include <bits/stdc++.h>
using namespace std;
struct fast_ios {
  fast_ios() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  };
} fast_ios_;
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 (long long 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<long long>;
using mat = vector<vec>;
using Pii = pair<long long, long long>;
using v_bool = vector<bool>;
using v_Pii = vector<Pii>;
const long long 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;
    long long i0 = 64 - __builtin_clzll(n);
    for (long long 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 mvec = vector<mint>;
using mmat = vector<mvec>;
struct Combination {
  vector<mint> fact, invfact;
  Combination(long long N) {
    fact = vector<mint>({mint(1)});
    invfact = vector<mint>({mint(1)});
    fact_initialize(N);
  }
  void fact_initialize(long long N) {
    long long i0 = fact.size();
    if (i0 >= N + 1) return;
    fact.resize(N + 1);
    invfact.resize(N + 1);
    for (long long i = i0; i <= N; i++) fact[i] = fact[i - 1] * i;
    invfact[N] = (mint)1 / fact[N];
    for (long long i = N - 1; i >= i0; i--)
      invfact[i] = invfact[i + 1] * (i + 1);
  }
  mint nCr(long long n, long long 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(long long n, long long 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(long long 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 (long long i = (1); i < (N); i++) {
      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(long long l, long long r, long long t) {
    if (t == n) return;
    long long sz = (r - l) >> 1;
    for (long long i = (0); i < (sz); i++) {
      f_tmp[l + i] = f[l + 2 * i];
      f_tmp[l + sz + i] = f[l + 2 * i + 1];
    }
    for (long long i = (l); i < (r); i++) f[i] = f_tmp[i];
    forward_exec(l, l + sz, t + 1);
    forward_exec(l + sz, r, t + 1);
    for (long long i = (0); i < (sz); i++)
      f_tmp[l + i] = f[l + i] + f[l + sz + i] * pow_e[i << t];
    for (long long i = (0); i < (sz); i++)
      f_tmp[l + sz + i] = f[l + i] + f[l + sz + i] * pow_e[(sz + i) << t];
    for (long long i = (l); i < (r); i++) f[i] = f_tmp[i];
  }
  void inverse_exec(long long l, long long r, long long t) {
    if (t == n) return;
    long long sz = (r - l) / 2;
    for (long long i = (0); i < (sz); i++) {
      f_tmp[l + i] = f[l + 2 * i];
      f_tmp[l + sz + i] = f[l + 2 * i + 1];
    }
    for (long long i = (l); i < (r); i++) f[i] = f_tmp[i];
    inverse_exec(l, l + sz, t + 1);
    inverse_exec(l + sz, r, t + 1);
    for (long long i = (0); i < (sz); i++)
      f_tmp[l + i] = f[l + i] + f[l + sz + i] * pow_e[N - (i << t)];
    for (long long i = (0); i < (sz); i++)
      f_tmp[l + sz + i] = f[l + i] + f[l + sz + i] * pow_e[N - ((sz + i) << t)];
    for (long long i = (l); i < (r); i++) f[i] = f_tmp[i];
  }

 public:
  long long N, n;
  ModInt<MOD> e, inv_N;
  vector<ModInt<MOD>> pow_e;
  NTT(long long 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();
  }
  NTT(long long 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) {
      for (long long i = (0); i < (N); i++) F[i] *= inv_N;
    }
  }
  vector<ModInt<MOD>> convolution(vector<ModInt<MOD>> A, vector<ModInt<MOD>> B,
                                  bool resize_result = false) {
    long long 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);
    for (long long i = (0); i < (N); i++) C[i] = A[i] * B[i];
    exec(C, true);
    if (resize_result) C.resize(sA + sB - 1);
    return C;
  }
};
signed main() {
  long long N;
  cin >> N;
  vec h(2 * N);
  cin >> h;
  const long long M = 100000;
  vec cnt(M);
  for (long long i = (0); i < (2 * N); i++) cnt[h[i] - 1]++;
  Combination C(M);
  mvec G(M + 1);
  G[0] = 1;
  for (long long i = (2); i < (M + 1); i++)
    if (i % 2 == 0) G[i] = G[i - 2] * (i - 1);
  mmat S;
  priority_queue<Pii, vector<Pii>, greater<Pii>> que;
  long long id = 0;
  for (long long i = (0); i < (M); i++)
    if (cnt[i] >= 2) {
      mvec tmp(cnt[i] / 2 + 1);
      for (long long n = (0); n < (cnt[i] / 2 + 1); n++)
        tmp[n] = C.nCr(cnt[i], 2 * n) * G[2 * n];
      S.push_back(tmp);
      que.push(Pii(((long long)tmp.size()), id));
      id++;
    }
  while (que.size() >= 2) {
    Pii p1 = que.top();
    que.pop();
    Pii p2 = que.top();
    que.pop();
    NTT<mod> ntt(p1.first + p2.first - 1);
    mvec tmp = ntt.convolution(S[p1.second], S[p2.second], true);
    S.push_back(tmp);
    que.push(Pii(((long long)tmp.size()), id));
    id++;
  }
  mint ans = 0;
  mvec num = S.back();
  for (long long i = (0); i < (((long long)num.size())); i++) {
    if (i % 2 == 0)
      ans += G[2 * (N - i)] * num[i];
    else
      ans -= G[2 * (N - i)] * num[i];
  }
  Out(ans);
  return 0;
}
