#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
#define fi first
#define se second
mt19937_64 eng(time(0) ^ clock());
template <typename T>
T rnd(T l, T r) { return eng() % (r - l + 1) + l; }
const int P = 998244353;
ll fac[10000005], inv[10000005], ifac[10000005];
void Init(int n) {
	fac[0] = fac[1] = inv[1] = ifac[0] = ifac[1] = 1;
	for (int i = 2; i <= n; i++) {
		fac[i] = fac[i - 1] * i % P;
		inv[i] = (P - P / i) * inv[P % i] % P;
		ifac[i] = ifac[i - 1] * inv[i] % P;
	}
}
ll Comb(int n, int m) {
	if (n < 0 || m < 0 || n < m)
		return 0;
	return fac[n] * ifac[m] % P * ifac[n - m] % P;
}
ll F(int n, int m) { return Comb(n + m, n); }
void Flip(int &x, int &y, int A) {
	// (x, y) | y = x + A;
	swap(x, y);
	x -= A, y += A;
}
int n, m;
ll Calc(int n, int m, int A, int B) {
	int x = n, y = m;
	ll res = F(n, m);
	while (1) {
		Flip(x, y, A);
		if (x < 0 || y < 0)
			break;
		(res += P - F(x, y)) %= P;
		Flip(x, y, B);
		if (x < 0 || y < 0)
			break;
		(res += F(x, y)) %= P;
	}
	x = n, y = m;
	while (1) {
		Flip(x, y, B);
		if (x < 0 || y < 0)
			break;
		(res += P - F(x, y)) %= P;
		Flip(x, y, A);
		if (x < 0 || y < 0)
			break;
		(res += F(x, y)) %= P;
	}
	return res;
}
int main() {
	scanf("%d%d", &n, &m);
	Init(n + 1);
	ll ans = 0;
	for (int i = 0; i <= (m + 1) / 2; i++)
		if ((i & 1) == (n & 1))
			(ans += Calc((n - i) / 2, (n + i) / 2 - 1, -2, (m + 1) / 2)) %= P;
	printf("%lld\n", ans);
	return 0;
}