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

const int N = 8e5 + 10;
const ll MOD = 998244353;

ll fact[N], ifact[N];
ll ksm(ll x, ll y){
    ll re = 1;
    for (; y; y >>= 1){
        if(y & 1) re = re * x % MOD;
        x = x * x % MOD;
    }
    return re;
}

ll C(int n, int m){if(n < 0 || m < 0 || n < m)return 0; return fact[n] * ifact[m] % MOD * ifact[n - m] % MOD;}

const long long g = 3, _g = ksm(3, MOD - 2);
int n, m;
int R[N << 2];
int limit = 1, L;
void NTT(long long *A, int op)
{
	for (int i = 0; i < limit; ++ i) if(i < R[i]) swap(A[i], A[R[i]]);
	for (int len = 1; len < limit; len <<= 1)
	{
		long long X = ksm(op == 1 ? g : _g, (MOD - 1) / (len << 1));
		for (int i = 0; i < limit; i += (len << 1))
		{
			long long pw = 1;
			for (int j = 0; j < len; ++ j)
			{
				long long x = A[i + j], y = pw * A[i + j + len] % MOD;
				A[i + j] = (x + y) % MOD; A[i + j + len] = (x - y + MOD) % MOD;
				pw = pw * X % MOD;
			}
		}
	}
}
void mul(long long *A, long long *B, int n, int m)
{
	limit = 1, L = 0;
	memset(R, 0, sizeof(R));
	while(limit <= n + m)limit <<= 1, ++ L;
	for (int i = 0; i < limit; ++ i)R[i] = (R[i >> 1] >> 1) | ((i & 1) << (L - 1));
	NTT(A, 1);
	NTT(B, 1);
	for (int i = 0; i < limit; ++ i)
	(A[i] *= B[i]) %= MOD;
	NTT(A, 0);
	long long div = ksm(limit, MOD - 2);
	for (int i = 0; i <= n + m; ++ i) (A[i] *= div) %= MOD;
}

long long A[N << 2], B[N << 2];


ll calc(int n, int m) {return C(n + m - 2, n - 1);}
ll Calc(int n, int m) {return (calc(n - 1, m - 1) * calc(n - 1, m - 1) % MOD - calc(n - 2, m) * calc(n, m - 2) % MOD + MOD) % MOD;}

int main() {
    ios::sync_with_stdio(0); cin.tie(0), cout.tie(0);

    fact[0] = 1;
    for (int i = 1; i < N; ++ i) fact[i] = fact[i - 1] * i % MOD;
    ifact[N - 1] = ksm(fact[N - 1], MOD - 2);
    for (int i = N - 2; ~i; -- i) ifact[i] = ifact[i + 1] * (i + 1) % MOD;

    int n, m;
    cin >> n >> m;
    ll ans = 0;

    
    // for (int i = 0; i <= n; ++ i)
    //     for (int j = 0; j <= m; ++ j)
    //         (ans += Calc(n - i + 1, m - j + 1) * (1 + (i != 0 || j != 0))) %= MOD;

	memset(A, 0, sizeof(A));
	memset(B, 0, sizeof(B));
    for (int i = 0; i <= n - 1; ++ i) A[i] = ifact[i] * ifact[i] % MOD;
    for (int i = 0; i <= m - 1; ++ i) B[i] = ifact[i] * ifact[i] % MOD;
    mul(A, B, n - 1, m - 1);
    for (int l = 0; l <= n + m - 2; ++ l) (ans += A[l] * fact[l] % MOD * fact[l]) %= MOD;
    
    
	memset(A, 0, sizeof(A));
	memset(B, 0, sizeof(B));
    for (int i = 1; i <= n - 1; ++ i) A[i] = ifact[i - 1] * ifact[i + 1] % MOD;
    for (int i = 1; i <= m - 1; ++ i) B[i] = ifact[i - 1] * ifact[i + 1] % MOD;
    mul(A, B, n - 1, m - 1);
    for (int l = 0; l <= n + m - 2; ++ l) (ans += MOD - A[l] * fact[l] % MOD * fact[l] % MOD) %= MOD;

    ans = (ans * 2 - Calc(n + 1, m + 1) + MOD) % MOD;

    for (int i = 2; i <= n - 1; ++ i) (ans += Calc(i, m + 1) * (n - i)) %= MOD;
    for (int i = 2; i <= m - 1; ++ i) (ans += Calc(n + 1, i) * (m - i)) %= MOD;

    cout << (ans + 2) % MOD;

}