//#define NDEBUG
#include <cstddef>
#include <cstdint>
#include <vector>

namespace n91 {

	using i8 = std::int_least8_t;
	using i32 = std::int_least32_t;
	using i64 = std::int_least64_t;
	using u8 = std::uint_least8_t;
	using u32 = std::uint_least32_t;
	using u64 = std::uint_least64_t;
	using isize = std::ptrdiff_t;
	using usize = std::size_t;

	class rep {
		const usize f, l;

	public:
		class itr {
			friend rep;
			usize i;
			constexpr itr(const usize x) noexcept : i(x) {}

		public:
			void operator++() noexcept { ++i; }
			constexpr usize operator*() const noexcept { return i; }
			constexpr bool operator!=(const itr x) const noexcept { return i != x.i; }
		};
		constexpr rep(const usize first, const usize last) noexcept
			: f(first), l(last) {}
		constexpr itr begin() const noexcept { return itr(f); }
		constexpr itr end() const noexcept { return itr(l); }
	};
	class revrep {
		const usize f, l;

	public:
		class itr {
			friend revrep;
			usize i;
			constexpr itr(usize x) noexcept : i(x) {}

		public:
			void operator++() noexcept { --i; }
			constexpr usize operator*() const noexcept { return i; }
			constexpr bool operator!=(const itr x) const noexcept { return i != x.i; }
		};
		constexpr revrep(usize first, usize last) noexcept : f(--first), l(--last) {}
		constexpr itr begin() const noexcept { return itr(l); }
		constexpr itr end() const noexcept { return itr(f); }
	};
	template <class T> using vec_alias = std::vector<T>;
	template <class T> auto md_vec(const usize n, const T &value) {
		return std::vector<T>(n, value);
	}
	template <class... Args> auto md_vec(const usize n, Args... args) {
		return std::vector<decltype(md_vec(args...))>(n, md_vec(args...));
	}
	template <class T> constexpr T difference(const T &a, const T &b) {
		return a < b ? b - a : a - b;
	}

} // namespace n91

#include <algorithm>
#include <iostream>
#include <utility>
#include <cassert>
#include <set>
#include <cstdio>

namespace n91 {

	template<class T>
	void scan(T&d,const int last) {
		d = 0;
		int c;
		while (c = fgetc(stdin), ('0' <= c&&c <= '9')) {
			d = d * 10 + c - '0';
		}
		assert(c == last);
	}

	void main_() {
		usize N;
		u32 L;
		scan(N, ' ');
		scan(L, '\n');
		assert(1 <= N&&N <= 100000);
		assert(2 * N < L&&L <= 1000000000);
		std::vector<u32> x(N), y(N);
		std::set<u32> z;
		for (const auto i : rep(0, N)) {
			scan(x[i], " \n"[i + 1 == N]);
			z.insert(x[i]);
			assert(0 < x[i]&&x[i] < L);
		}
		for (usize i = 1;i != N;++i) {
			assert(x[i - 1] < x[i]);
		}
		for (const auto i : rep(0, N)) {
			scan(y[i], " \n"[i + 1 == N]);
			z.insert(y[i]);
			assert(0 < y[i] && y[i] < L);
		}
		for (usize i = 1;i != N;++i) {
			assert(y[i - 1] < y[i]);
		}
		assert(z.size() == 2 * N);
		return;
	}

} // namespace n91

int main() {
	n91::main_();
	return 0;
}