#include #include #include using std::cin; using std::cout; const char endl = '\n'; const int N = 2005; const int mod = 1e9 + 9; int n, k, inv[N], fac[N], inv_fac[N], a[N], b[N], l[N], f[N][N], g[N], ans; inline int C(int n, int m) { return static_cast(fac[n]) * inv_fac[m] % mod * inv_fac[n - m] % mod; } int main() { std::ios::sync_with_stdio(false); cin.tie(nullptr); fac[0] = 1; for (int i = 1; i < N; i++) { fac[i] = static_cast(fac[i - 1]) * i % mod; } inv[0] = inv[1] = 1; for (int i = 2; i < N; i++) { inv[i] = static_cast(mod - (mod / i)) * inv[mod % i] % mod; } inv_fac[0] = inv_fac[1] = 1; for (int i = 2; i < N; i++) { inv_fac[i] = static_cast(inv_fac[i - 1]) * inv[i] % mod; } cin >> n >> k; if ((n - k) % 2 == 1) { cout << 0 << endl; exit(0); } std::copy_n(std::istream_iterator(cin), n, a + 1); std::copy_n(std::istream_iterator(cin), n, b + 1); std::sort(a + 1, a + 1 + n); std::sort(b + 1, b + 1 + n); std::transform(a + 1, a + 1 + n, l + 1, [&](int x) { return std::distance(b + 1, std::lower_bound(b + 1, b + 1 + n, x)); }); f[0][0] = 1; for (int i = 1; i <= n; i++) { f[i][0] = f[i - 1][0]; for (int j = 1; j <= i; j++) { f[i][j] = (static_cast(f[i - 1][j]) + static_cast(f[i - 1][j - 1]) * (l[i] - j + 1) % mod) % mod; } } for (int i = 0; i <= n; i++) { g[i] = static_cast(f[n][i]) * fac[n - i] % mod; } int w = (n + k) >> 1; for (int i = w; i <= n; i++) { if ((i - w) & 1) { ans = (static_cast(ans) - static_cast(C(i, w)) * g[i] % mod + mod) % mod; } else { ans = (static_cast(ans) + static_cast(C(i, w)) * g[i] % mod) % mod; } } cout << ans << endl; return 0; }