#include <bits/stdc++.h>

#ifdef DEBUG
#include <Mylib/Debug/debug.cpp>
#else
#define dump(...) ((void)0)
#endif

template <typename T, typename U>
bool chmin(T &a, const U &b){
  return (a > b ? a = b, true : false);
}

template <typename T, typename U>
bool chmax(T &a, const U &b){
  return (a < b ? a = b, true : false);
}

template <typename T, size_t N, typename U>
void fill_array(T (&a)[N], const U &v){
  std::fill((U*)a, (U*)(a + N), v);
}

template <typename T, size_t N, size_t I = N>
auto make_vector(const std::array<int, N> &a, T value = T()){
  static_assert(I >= 1);
  static_assert(N >= 1);
  if constexpr (I == 1){
    return std::vector<T>(a[N - I], value);
  }else{
    return std::vector(a[N - I], make_vector<T, N, I - 1>(a, value));
  }
}

template <typename T>
std::ostream& operator<<(std::ostream &s, const std::vector<T> &a){
  for(auto it = a.begin(); it != a.end(); ++it){
    if(it != a.begin()) s << " ";
    s << *it;
  }
  return s;
}

template <typename T>
std::istream& operator>>(std::istream &s, std::vector<T> &a){
  for(auto &x : a) s >> x;
  return s;
}

namespace haar_lib {
  template <int32_t M>
  class modint {
    uint32_t val;

  public:
    constexpr static auto mod(){return M;}

    constexpr modint(): val(0){}
    constexpr modint(int64_t n){
      if(n >= M) val = n % M;
      else if(n < 0) val = n % M + M;
      else val = n;
    }

    constexpr auto& operator=(const modint &a){val = a.val; return *this;}
    constexpr auto& operator+=(const modint &a){
      if(val + a.val >= M) val = (uint64_t)val + a.val - M;
      else val += a.val;
      return *this;
    }
    constexpr auto& operator-=(const modint &a){
      if(val < a.val) val += M;
      val -= a.val;
      return *this;
    }
    constexpr auto& operator*=(const modint &a){
      val = (uint64_t)val * a.val % M;
      return *this;
    }
    constexpr auto& operator/=(const modint &a){
      val = (uint64_t)val * a.inv().val % M;
      return *this;
    }

    constexpr auto operator+(const modint &a) const {return modint(*this) += a;}
    constexpr auto operator-(const modint &a) const {return modint(*this) -= a;}
    constexpr auto operator*(const modint &a) const {return modint(*this) *= a;}
    constexpr auto operator/(const modint &a) const {return modint(*this) /= a;}

    constexpr bool operator==(const modint &a) const {return val == a.val;}
    constexpr bool operator!=(const modint &a) const {return val != a.val;}

    constexpr auto& operator++(){*this += 1; return *this;}
    constexpr auto& operator--(){*this -= 1; return *this;}

    constexpr auto operator++(int){auto t = *this; *this += 1; return t;}
    constexpr auto operator--(int){auto t = *this; *this -= 1; return t;}

    constexpr static modint pow(int64_t n, int64_t p){
      if(p < 0) return pow(n, -p).inv();

      int64_t ret = 1, e = n % M;
      for(; p; (e *= e) %= M, p >>= 1) if(p & 1) (ret *= e) %= M;
      return ret;
    }

    constexpr static modint inv(int64_t a){
      int64_t b = M, u = 1, v = 0;

      while(b){
        int64_t t = a / b;
        a -= t * b; std::swap(a, b);
        u -= t * v; std::swap(u, v);
      }

      u %= M;
      if(u < 0) u += M;

      return u;
    }

    constexpr static auto frac(int64_t a, int64_t b){return modint(a) / modint(b);}

    constexpr auto pow(int64_t p) const {return pow(val, p);}
    constexpr auto inv() const {return inv(val);}

    friend constexpr auto operator-(const modint &a){return modint(M - a.val);}

    friend constexpr auto operator+(int64_t a, const modint &b){return modint(a) + b;}
    friend constexpr auto operator-(int64_t a, const modint &b){return modint(a) - b;}
    friend constexpr auto operator*(int64_t a, const modint &b){return modint(a) * b;}
    friend constexpr auto operator/(int64_t a, const modint &b){return modint(a) / b;}

    friend std::istream& operator>>(std::istream &s, modint<M> &a){s >> a.val; return s;}
    friend std::ostream& operator<<(std::ostream &s, const modint<M> &a){s << a.val; return s;}

    template <int N>
    static auto div(){
      static auto value = inv(N);
      return value;
    }

    explicit operator int32_t() const noexcept {return val;}
    explicit operator int64_t() const noexcept {return val;}
  };
}

namespace haar_lib {
  template <typename T>
  class factorial_table {
  public:
    using value_type = T;

  private:
    std::vector<T> f_table;
    std::vector<T> if_table;

  public:
    factorial_table(int N){
      f_table.assign(N + 1, 1);
      if_table.assign(N + 1, 1);

      for(int i = 1; i <= N; ++i){
        f_table[i] = f_table[i - 1] * i;
      }

      if_table[N] = f_table[N].inv();

      for(int i = N; --i >= 0;){
        if_table[i] = if_table[i + 1] * (i + 1);
      }
    }

    T factorial(int64_t i) const {
      assert(i < (int)f_table.size());
      return f_table[i];
    }

    T inv_factorial(int64_t i) const {
      assert(i < (int)if_table.size());
      return if_table[i];
    }

    T P(int64_t n, int64_t k) const {
      if(n < k or n < 0 or k < 0) return 0;
      return factorial(n) * inv_factorial(n - k);
    }

    T C(int64_t n, int64_t k) const {
      if(n < k or n < 0 or k < 0) return 0;
      return P(n, k) * inv_factorial(k);
    }

    T H(int64_t n, int64_t k) const {
      if(n == 0 and k == 0) return 1;
      return C(n + k - 1, k);
    }
  };
}


namespace haar_lib {
  template <typename T, int PRIM_ROOT, int MAX_SIZE>
  class number_theoretic_transform {
  public:
    using value_type = T;
    constexpr static int primitive_root = PRIM_ROOT;

  private:
    const int MAX_POWER;
    std::vector<T> BASE, INV_BASE;

  public:
    number_theoretic_transform():
      MAX_POWER(__builtin_ctz(MAX_SIZE)),
      BASE(MAX_POWER + 1),
      INV_BASE(MAX_POWER + 1)
    {
      static_assert((MAX_SIZE & (MAX_SIZE - 1)) == 0, "MAX_SIZE must be power of 2.");

      T t = T::pow(PRIM_ROOT, (T::mod() - 1) >> (MAX_POWER + 2));
      T s = t.inv();

      for(int i = MAX_POWER - 1; i >= 0; --i){
        t *= t;
        s *= s;
        BASE[i] = -t;
        INV_BASE[i] = -s;
      }
    }

    void run(std::vector<T> &f, bool INVERSE = false){
      const int n = f.size();
      assert((n & (n - 1)) == 0 and n <= MAX_SIZE); // データ数は2の冪乗個

      if(INVERSE){
        for(int b = 1; b < n; b <<= 1){
          T w = 1;
          for(int j = 0, k = 1; j < n; j += 2 * b, ++k){
            for(int i = 0; i < b; ++i){
              const auto s = f[i + j];
              const auto t = f[i + j + b];

              f[i + j] = s + t;
              f[i + j + b] = (s - t) * w;
            }
            w *= INV_BASE[__builtin_ctz(k)];
          }
        }

        const T t = T::inv(n);
        for(auto &x : f) x *= t;
      }else{
        for(int b = n >> 1; b; b >>= 1){
          T w = 1;
          for(int j = 0, k = 1; j < n; j += 2 * b, ++k){
            for(int i = 0; i < b; ++i){
              const auto s = f[i + j];
              const auto t = f[i + j + b] * w;

              f[i + j] = s + t;
              f[i + j + b] = s - t;
            }
            w *= BASE[__builtin_ctz(k)];
          }
        }
      }
    }

    template <typename U>
    std::vector<T> convolve(std::vector<U> f, std::vector<U> g){
      const int m = f.size() + g.size() - 1;
      int n = 1;
      while(n < m) n *= 2;

      std::vector<T> f2(n), g2(n);

      for(int i = 0; i < (int)f.size(); ++i) f2[i] = f[i];
      for(int i = 0; i < (int)g.size(); ++i) g2[i] = g[i];

      run(f2);
      run(g2);

      for(int i = 0; i < n; ++i) f2[i] *= g2[i];
      run(f2, true);

      return f2;
    }
  };

  template <typename T, typename U>
  std::vector<T> convolve_general_mod(std::vector<U> f, std::vector<U> g){
    static constexpr int M1 = 167772161, P1 = 3;
    static constexpr int M2 = 469762049, P2 = 3;
    static constexpr int M3 = 1224736769, P3 = 3;

    for(auto &x : f) x %= T::mod();
    for(auto &x : g) x %= T::mod();

    auto res1 = number_theoretic_transform<modint<M1>, P1, 1 << 20>().convolve(f, g);
    auto res2 = number_theoretic_transform<modint<M2>, P2, 1 << 20>().convolve(f, g);
    auto res3 = number_theoretic_transform<modint<M3>, P3, 1 << 20>().convolve(f, g);

    const int n = res1.size();

    std::vector<T> ret(n);

    const int64_t M12 = (int64_t)modint<M2>::inv(M1);
    const int64_t M13 = (int64_t)modint<M3>::inv(M1);
    const int64_t M23 = (int64_t)modint<M3>::inv(M2);

    for(int i = 0; i < n; ++i){
      const int64_t r[3] = {(int64_t)res1[i], (int64_t)res2[i], (int64_t)res3[i]};

      const int64_t t0 = r[0] % M1;
      const int64_t t1 = (r[1] - t0 + M2) * M12 % M2;
      const int64_t t2 = ((r[2] - t0 + M3) * M13 % M3 - t1 + M3) * M23 % M3;

      ret[i] = T(t0) + T(t1) * M1 + T(t2) * M1 * M2;
    }

    return ret;
  }
}




namespace haar_lib {
  template <typename T>
  class semifactorial {
    std::vector<T> data_;

  public:
    semifactorial(int N): data_(N + 1, 1){
      for(int i = 2; i <= N; i += 2) data_[i] = data_[i - 2] * i;
      for(int i = 3; i <= N; i += 2) data_[i] = data_[i - 2] * i;
    }

    T operator()(int i) const {
      assert(0 <= i);
      return data_[i];
    }
  };
}




namespace haar_lib {}

namespace solver {
  using namespace haar_lib;

  constexpr int m1000000007 = 1000000007;
  constexpr int m998244353 = 998244353;

  void init(){
    std::cin.tie(0);
    std::ios::sync_with_stdio(false);
    std::cout << std::fixed << std::setprecision(12);
    std::cerr << std::fixed << std::setprecision(12);
    std::cin.exceptions(std::ios_base::failbit);
  }

  using mint = modint<m998244353>;
  constexpr int PRIM = 3;
  constexpr int MAX = 100000;

  void solve(){
    int N; std::cin >> N;
    std::vector<int> h(2 * N); std::cin >> h;

    std::vector<int> count(MAX);
    for(int i = 0; i < 2 * N; ++i) count[h[i] - 1] += 1;

    count.erase(
      std::remove_if(count.begin(), count.end(), [](const auto &a){return a == 0;}),
      count.end()
    );

    dump(count);

    auto sf = semifactorial<mint>(2 * N);
    auto ft = factorial_table<mint>(2 * N);
    auto ntt = number_theoretic_transform<mint, PRIM, 1 << 20>();

    std::vector<std::vector<mint>> a;
    for(auto x : count){
      std::vector<mint> temp;

      temp.push_back(1);

      for(int i = 1; i <= x / 2; ++i){
        temp.push_back(ft.C(x, x - 2 * i) * sf(2 * i - 1));
      }

      //dump(temp);

      a.push_back(temp);
    }

    const int K = a.size();

    std::vector<int> len(K);
    std::priority_queue<std::pair<int, int>, std::vector<std::pair<int, int>>, std::greater<>> pq;

    for(int i = 0; i < K; ++i){
      len[i] = a[i].size();
      pq.emplace(len[i], i);
    }


    while(pq.size() > 1){
      auto [li, i] = pq.top(); pq.pop();
      auto [lj, j] = pq.top(); pq.pop();

      a[i] = ntt.convolve(a[i], a[j]);
      a[i].resize(li + lj - 1);

      pq.emplace(a[i].size(), i);
    }

    std::vector<mint> d = a[pq.top().second];

    d.resize(N + 1);

    dump(d);

    for(int i = 0; i < N; ++i){
      d[i] *= sf(2 * N - 2 * i - 1);
    }

    dump(d);

    mint ans = 0;
    for(int i = 0; i <= N; ++i){
      if(i % 2) ans -= d[i];
      else ans += d[i];
    }

    std::cout << ans << "\n";
  }
}

int main(){
  solver::init();
  while(true){
    try{
      solver::solve();
    }catch(const std::istream::failure &e){
      break;
    }
  }
  return 0;
}


Measured memory_bytes: 12840