#include <iostream>
#include <vector>
#include <map>
#include <queue>

template <class T>
using MinHeap = std::priority_queue<T, std::vector<T>, std::greater<T>>;

template <int MOD>
struct ModInt {
    using lint = long long;
    int val;

    // constructor
    ModInt(lint v = 0) : val(v % MOD) {
        if (val < 0) val += MOD;
    };

    // unary operator
    ModInt operator+() const { return ModInt(val); }
    ModInt operator-() const { return ModInt(MOD - val); }
    ModInt inv() const { return this->pow(MOD - 2); }

    // arithmetic
    ModInt operator+(const ModInt& x) const { return ModInt(*this) += x; }
    ModInt operator-(const ModInt& x) const { return ModInt(*this) -= x; }
    ModInt operator*(const ModInt& x) const { return ModInt(*this) *= x; }
    ModInt operator/(const ModInt& x) const { return ModInt(*this) /= x; }
    ModInt pow(lint n) const {
        auto x = ModInt(1);
        auto b = *this;
        while (n > 0) {
            if (n & 1) x *= b;
            n >>= 1;
            b *= b;
        }
        return x;
    }

    // compound assignment
    ModInt& operator+=(const ModInt& x) {
        if ((val += x.val) >= MOD) val -= MOD;
        return *this;
    }
    ModInt& operator-=(const ModInt& x) {
        if ((val -= x.val) < 0) val += MOD;
        return *this;
    }
    ModInt& operator*=(const ModInt& x) {
        val = lint(val) * x.val % MOD;
        return *this;
    }
    ModInt& operator/=(const ModInt& x) { return *this *= x.inv(); }

    // compare
    bool operator==(const ModInt& b) const { return val == b.val; }
    bool operator!=(const ModInt& b) const { return val != b.val; }
    bool operator<(const ModInt& b) const { return val < b.val; }
    bool operator<=(const ModInt& b) const { return val <= b.val; }
    bool operator>(const ModInt& b) const { return val > b.val; }
    bool operator>=(const ModInt& b) const { return val >= b.val; }

    // I/O
    friend std::istream& operator>>(std::istream& is, ModInt& x) noexcept {
        lint v;
        is >> v;
        x = v;
        return is;
    }
    friend std::ostream& operator<<(std::ostream& os, const ModInt& x) noexcept { return os << x.val; }
};

template <int MOD, int Root>
struct NumberTheoreticalTransform {
    using mint = ModInt<MOD>;
    using mints = std::vector<mint>;

    // the 2^k-th root of 1
    std::vector<mint> zetas;

    explicit NumberTheoreticalTransform() {
        int exp = MOD - 1;
        while (true) {
            mint zeta = mint(Root).pow(exp);
            zetas.push_back(zeta);
            if (exp & 1) break;
            exp /= 2;
        }
    }

    // ceil(log_2 n)
    static int clog2(int n) {
        int k = 0;
        while ((1 << k) < n) ++k;
        return k;
    }

    // 2-radix cooley-tukey algorithm without bit reverse
    // the size of f must be a power of 2
    void ntt(mints& f) const {
        int n = f.size();

        for (int m = n >> 1; m >= 1; m >>= 1) {
            auto zeta = zetas[clog2(m) + 1];
            mint zetapow(1);

            for (int p = 0; p < m; ++p) {
                for (int s = 0; s < n; s += (m << 1)) {
                    auto l = f[s + p],
                         r = f[s + p + m];

                    f[s + p] = l + r;
                    f[s + p + m] = (l - r) * zetapow;
                }
                zetapow = zetapow * zeta;
            }
        }
    }

    // the inverse of above function
    void intt(mints& f) const {
        int n = f.size();

        for (int m = 1; m <= (n >> 1); m <<= 1) {
            auto zeta = zetas[clog2(m) + 1].inv();
            mint zetapow(1);

            for (int p = 0; p < m; ++p) {
                for (int s = 0; s < n; s += (m << 1)) {
                    auto l = f[s + p],
                         r = f[s + p + m] * zetapow;

                    f[s + p] = l + r;
                    f[s + p + m] = l - r;
                }
                zetapow = zetapow * zeta;
            }
        }

        auto ninv = mint(n).inv();
        for (auto& x : f) x *= ninv;
    }

    mints convolute(mints f, mints g) const {
        int fsz = f.size(),
            gsz = g.size();

        // simple convolution in small cases
        if (std::min(fsz, gsz) < 8) {
            mints ret(fsz + gsz - 1, 0);
            for (int i = 0; i < fsz; ++i) {
                for (int j = 0; j < gsz; ++j) {
                    ret[i + j] += f[i] * g[j];
                }
            }
            return ret;
        }

        int n = 1 << clog2(fsz + gsz - 1);
        f.resize(n, mint(0));
        g.resize(n, mint(0));

        ntt(f);
        ntt(g);

        for (int i = 0; i < n; ++i) f[i] *= g[i];

        intt(f);

        f.resize(fsz + gsz - 1);
        return f;
    }
};

template <class T>
struct Combination {
    int max_n;
    std::vector<T> f, invf;

    explicit Combination(int n)
        : max_n(n), f(n + 1), invf(n + 1) {
        f[0] = 1;
        for (int i = 1; i <= n; ++i) {
            f[i] = f[i - 1] * i;
        }

        invf[max_n] = f[max_n].inv();
        for (int i = max_n - 1; i >= 0; --i) {
            invf[i] = invf[i + 1] * (i + 1);
        }
    }

    T fact(int n) const { return n < 0 ? T(0) : f[n]; }
    T invfact(int n) const { return n < 0 ? T(0) : invf[n]; }
    T perm(int a, int b) const {
        return a < b || b < 0 ? T(0) : f[a] * invf[a - b];
    }
    T binom(int a, int b) const {
        return a < b || b < 0 ? T(0) : f[a] * invf[a - b] * invf[b];
    }
};

constexpr int MOD = 998244353;
using mint = ModInt<MOD>;

const Combination<mint> C(1000000);
const NumberTheoreticalTransform<MOD, 3> ntt;

struct Poly {
    std::vector<mint> poly;
    Poly(const std::vector<mint>& poly) : poly(poly) {}

    bool operator>(const Poly& other) const {
        return poly.size() > other.poly.size();
    }
};

void solve() {
    int n;
    std::cin >> n;
    n <<= 1;

    std::map<int, int> cnt;
    for (int i = 0; i < n; ++i) {
        int x;
        std::cin >> x;

        if (!cnt.count(x)) cnt[x] = 0;
        ++cnt[x];
    }

    MinHeap<Poly> polys;
    for (auto [x, m] : cnt) {
        std::vector<mint> f;
        for (int k = 0; k * 2 <= m; ++k) {
            f.push_back(C.perm(m, k * 2) /
                        (mint(2).pow(k) * C.fact(k)));
        }
        polys.emplace(f);
    }

    while ((int)polys.size() > 1) {
        auto f = polys.top();
        polys.pop();
        auto g = polys.top();
        polys.pop();
        auto h = ntt.convolute(f.poly, g.poly);
        polys.emplace(h);
    }

    auto pat = polys.top().poly;
    mint ans = 0;
    for (int k = 0; k < (int)pat.size(); ++k) {
        int num = n - k * 2;
        ans += mint(-1).pow(k) * pat[k] *
               C.perm(num, num / 2) / mint(2).pow(num / 2);
    }

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

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}


Measured memory_bytes: 21256