#include <bits/stdc++.h>
using namespace std;

const int mod = 998244353;
const int N = 8e5 + 5;
int fac[N], ifac[N];
int inv(int x)
{
	int res = 1, y = mod - 2;
	while (y)
	{
		if (y & 1) res = 1ll * res * x % mod;
		x = 1ll * x * x % mod;
		y >>= 1;
	}
	return res;
}
int binom(int x, int y)
{
	if (x < 0 or y < 0 or x < y) return 0;
	return 1ll * fac[x] * ifac[y] % mod * ifac[x - y] % mod;
}
int cal(int x, int y)
{
	int ret = 1ll * binom(x + y - 2, x - 1) * binom(x + y - 2, y - 1) % mod;
	ret = (ret + mod - 1ll * binom(x + y - 2, x - 2) * binom(x + y - 2, y - 2) % mod) % mod;
	return ret;
}

int main() 
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	
	fac[0] = 1;
	for (int i = 1; i <= 800000; i++)
		fac[i] = 1ll * fac[i - 1] * i % mod;
	ifac[800000] = inv(fac[800000]);
	for (int i = 799999; i >= 0; i--)
		ifac[i] = 1ll * ifac[i + 1] * (i + 1) % mod;
	
	int n, m;
	cin >> n >> m;
	int ans = 2;
	for (int i = 1; i <= n; i++) ans = (ans + 1ll * (n - i + 1) * cal(i, m) % mod) % mod;
	for (int i = 1; i < m; i++) ans = (ans + 1ll * (m - i) * cal(n, i) % mod) % mod;
	
	for (int t = 0; t <= n + m - 3; t++) ans = (ans + binom(t * 2, t)) % mod;
	for (int t = 0; t <= n + m - 2; t++) ans = (ans + binom(t * 2, t - 4)) % mod;
//	for (int i = 1; i <= n; i++)
//	{
//		// for (int j = i + 1; j <= n; j++) ans = (ans + cal(j - i, m)) % mod;
//		for (int j = 1; j < m; j++) ans = (ans + cal(i, j)) % mod;
//	}
//	for (int i = 1; i < m; i++)
//	{
//		// for (int j = i + 1; j <= m; j++) ans = (ans + cal(n, j - i)) % mod;
//		for (int j = 1; j < n; j++) ans = (ans + cal(j, i)) % mod;
//	}
	cout << ans << '\n';
}