//#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 <cstdint>

template <std::uint_fast64_t Modulus> class modint {
	using u64 = std::uint_fast64_t;

public:
	u64 a;

	constexpr modint(const u64 x = 0) noexcept : a(x % Modulus) {}
	constexpr u64 &value() noexcept { return a; }
	constexpr const u64 &value() const noexcept { return a; }
	constexpr modint operator+(const modint rhs) const noexcept {
		return modint(*this) += rhs;
	}
	constexpr modint operator-(const modint rhs) const noexcept {
		return modint(*this) -= rhs;
	}
	constexpr modint operator*(const modint rhs) const noexcept {
		return modint(*this) *= rhs;
	}
	constexpr modint operator/(const modint rhs) const noexcept {
		return modint(*this) /= rhs;
	}
	constexpr modint &operator+=(const modint rhs) noexcept {
		a += rhs.a;
		if (a >= Modulus) {
			a -= Modulus;
		}
		return *this;
	}
	constexpr modint &operator-=(const modint rhs) noexcept {
		if (a < rhs.a) {
			a += Modulus;
		}
		a -= rhs.a;
		return *this;
	}
	constexpr modint &operator*=(const modint rhs) noexcept {
		a = a * rhs.a % Modulus;
		return *this;
	}
	constexpr modint &operator/=(modint rhs) noexcept {
		u64 exp = Modulus - 2;
		while (exp) {
			if (exp % 2) {
				*this *= rhs;
			}
			rhs *= rhs;
			exp /= 2;
		}
		return *this;
	}
};

#include <algorithm>
#include <iostream>
#include <string>
#include <utility>

namespace n91 {

	void main_() {
		using mint = modint<998244353>;
		usize n, x;
		std::cin >> n >> x;
		const usize f_max = (n + x + 1) * 2;
		std::vector<mint> fact(f_max + 1), ifac(f_max + 1);
		fact[0] = 1;
		for (const auto i : rep(1, f_max + 1)) {
			fact[i] = fact[i - 1] * i;
		}
		ifac[f_max] = mint(1) / fact[f_max];
		for (const auto i : revrep(1, f_max + 1)) {
			ifac[i - 1] = ifac[i] * i;
		}
		const auto binom = [&](const usize n, const usize r) {
			return fact[n] * ifac[r] * ifac[n - r];
		};
		mint ans = 0;
		if (x % 2 == 0) {
			std::vector<mint> count(n + x + 1);
			for (const auto i : rep(0, x)) {
				for (usize j = 0; j * 2 <= i; ++j) {
					count[i - j] += binom(i - j, j);
				}
			}
			for (usize i = x + 1; i <= 2 * x - 3; i += 2) {
				const usize rem = 2 * x - i - 2;
				for (usize j = 0; j * 2 <= rem; ++j) {
					count[x - 1 - j] += binom(rem - j, j);
				}
			}
			for (const auto i : rep(0, n + 1)) {
				ans += count[i] * binom(n, i);
			}
		}
		else {
			std::vector<mint> count(n + x + 1);
			if (x != 1) {
				for (const auto i : rep(0, x)) {
					for (usize j = 0; j * 2 <= i; ++j) {
						count[i - j] += binom(i - j, j);
					}
				}
			}
			for (usize i = x + 1; i < 2 * x - 2; i += 2) {
				const usize rem = 2 * x - i - 2;
				for (usize j = 0; j * 2 <= rem; ++j) {
					count[x - 1 - j] += binom(rem - j, j);
				}
			}
			for (usize i = 2 * x - 2; i / 2 <= n; i += 2) {
				count[i / 2] += 1;
			}
			for (const auto i : rep(0, n + 1)) {
				ans += count[i] * binom(n, i);
			}
		}
		std::cout << ans.value() << std::endl;
	}

} // namespace n91

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


Measured memory_bytes: 640