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

constexpr int mod = 998244353;

long long fac[400005], finv[400005], inv[400005];

void COMinit() {
    fac[0] = fac[1] = finv[0] = finv[1] = inv[1] = 1;
    for (int i = 2; i < 400005; i++) {
        fac[i] = fac[i - 1] * i % mod;
        inv[i] = mod - inv[mod % i] * (mod / i) % mod;
        finv[i] = finv[i - 1] * inv[i] % mod;
    }
}

long long COM(int n, int k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % mod) % mod;
}

long long choose(int n,int k) {
    if(n < 0 || k < 0) return 0;
    if(n == 0) return 1;
    return COM(n+k-1,k-1);
}

template< int mod >
struct NumberTheoreticTransform {
    
    vector< int > rev, rts;
    int base, max_base, root;
    
    NumberTheoreticTransform() : base(1), rev{0, 1}, rts{0, 1} {
        assert(mod >= 3 && mod % 2 == 1);
        auto tmp = mod - 1;
        max_base = 0;
        while(tmp % 2 == 0) tmp >>= 1, max_base++;
        root = 2;
        while(mod_pow(root, (mod - 1) >> 1) == 1) ++root;
        assert(mod_pow(root, mod - 1) == 1);
        root = mod_pow(root, (mod - 1) >> max_base);
    }
    
    inline int mod_pow(int x, int n) {
        int ret = 1;
        while(n > 0) {
            if(n & 1) ret = mul(ret, x);
            x = mul(x, x);
            n >>= 1;
        }
        return ret;
    }
    
    inline int inverse(int x) {
        return mod_pow(x, mod - 2);
    }
    
    inline unsigned add(unsigned x, unsigned y) {
        x += y;
        if(x >= mod) x -= mod;
        return x;
    }
    
    inline unsigned mul(unsigned a, unsigned b) {
        return 1ull * a * b % (unsigned long long) mod;
    }
    
    void ensure_base(int nbase) {
        if(nbase <= base) return;
        rev.resize(1 << nbase);
        rts.resize(1 << nbase);
        for(int i = 0; i < (1 << nbase); i++) {
            rev[i] = (rev[i >> 1] >> 1) + ((i & 1) << (nbase - 1));
        }
        assert(nbase <= max_base);
        while(base < nbase) {
            int z = mod_pow(root, 1 << (max_base - 1 - base));
            for(int i = 1 << (base - 1); i < (1 << base); i++) {
                rts[i << 1] = rts[i];
                rts[(i << 1) + 1] = mul(rts[i], z);
            }
            ++base;
        }
    }
    
    void ntt(vector< int > &a) {
        const int n = (int) a.size();
        assert((n & (n - 1)) == 0);
        int zeros = __builtin_ctz(n);
        ensure_base(zeros);
        int shift = base - zeros;
        for(int i = 0; i < n; i++) {
            if(i < (rev[i] >> shift)) {
                swap(a[i], a[rev[i] >> shift]);
            }
        }
        for(int k = 1; k < n; k <<= 1) {
            for(int i = 0; i < n; i += 2 * k) {
                for(int j = 0; j < k; j++) {
                    int z = mul(a[i + j + k], rts[j + k]);
                    a[i + j + k] = add(a[i + j], mod - z);
                    a[i + j] = add(a[i + j], z);
                }
            }
        }
    }
    
    vector< int > multiply(vector< int > a, vector< int > b) {
        int need = a.size() + b.size() - 1;
        int nbase = 1;
        while((1 << nbase) < need) nbase++;
        ensure_base(nbase);
        int sz = 1 << nbase;
        a.resize(sz, 0);
        b.resize(sz, 0);
        ntt(a);
        ntt(b);
        int inv_sz = inverse(sz);
        for(int i = 0; i < sz; i++) {
            a[i] = mul(a[i], mul(b[i], inv_sz));
        }
        reverse(a.begin() + 1, a.end());
        ntt(a);
        a.resize(need);
        return a;
    }
};

int main() {
    COMinit();
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int H,W;
    cin >> H >> W;
    vector<int>tmp1(H+1),tmp2(W+1);
    for(int i = 1; i <= H; i++) {
        tmp1[i] = COM(i,H-i)*finv[i]%mod;
    }
    for(int i = 1; i <= W; i++) {
        tmp2[i] = COM(i,W-i)*finv[i]%mod;
    }
    NumberTheoreticTransform<mod>ntt;
    vector<int>ans = ntt.multiply(tmp1,tmp2);
    int fans = 0;
    for(int i = 2; i <= H+W; i++) {
        fans += ans[i]*fac[i]%mod;
        if(fans >= mod) fans -= mod;
    }
    cout << fans << "\n";
}