#include <bits/stdc++.h>

using namespace std;

const int mod = 998244353, o = 19, len = 1 << o;
int n, m, fac[len], ifac[len];
int f[len], g[len];
int power(int a, int n) {
    int tp = 1;
    while (n) {
        if (n & 1) {
            tp = 1ll * tp * a % mod;
        }
        a = 1ll * a * a % mod, n >>= 1;
    }
    return tp;
}

int c(int n, int m) { return n < m || m < 0 ? 0 : 1ll * fac[n] * ifac[m] % mod * ifac[n - m] % mod; }

void prep(int n) {
    fac[0] = 1;
    for (int i = 1; i <= n; i++) {
        fac[i] = 1ll * fac[i - 1] * i % mod;
    }
    ifac[n] = power(fac[n], mod - 2);
    for (int i = n - 1; i != -1; i--) {
        ifac[i] = 1ll * ifac[i + 1] * (i + 1) % mod;
    }
}

namespace poly {
using u64 = unsigned long long;
int r[len], w[len], up, l;

void init() {
    int w1 = power(3, (mod - 1) >> o);
    w[len >> 1] = 1;
    for (int i = (len >> 1) + 1; i != len; i++) {
        w[i] = 1ll * w[i - 1] * w1 % mod;
    }
    for (int i = (len >> 1) -1; i; i--) {
        w[i] = w[i << 1];
    }

    for (int i = 0; i != len; i++) {
        r[i] = (r[i >> 1] >> 1) | ((i & 1) << (o - 1));
    }
}

void ntt(int *a, int n, bool op) {
    static u64 t[len];
    for (int i = 0; i != n; i += 2) {
        int x = a[r[i] >> (o - l)], y = a[r[i + 1] >> (o - l)];
        t[i] = x + y, t[i + 1] = x + mod - y;
    }
    for (int l = 2; l != n; l <<= 1) {
        int *k = w + l;
        if (l == 1 << 18) {
            for (u64 *f = t; f != t + n; f++) {
                *f %= mod;
            }
        }
        for (u64 *f = t; f != t + n; f += l) {
            for (int *j = k; j != k + l; j++, f++) {
                u64 x = *f, y = f[l] * *j % mod;
                f[l] = x + mod - y, *f += y;
            }
        }
    }

    if (op) {
        for (int i = 0, x = mod - (mod >> l); i != n; i++) {
            a[i] = t[i] % mod * x % mod;
        }
        reverse(a + 1, a + n);
    } else {
        for (int i = 0; i != n; i++) {
            a[i] = t[i] % mod;
        }
    }
}

int pre(int n) {
    l = __lg(n) + 1;
    return up = 1 << l;
}
}

int main(){
    cin >> n >> m;
    prep(n + m);
    poly::init();

    for (int i = 0; i != n; i++) {
        f[i] = 1ll * ifac[i] * ifac[i] % mod;
    }
    for (int i = 0; i != m; i++) {
        g[i] = 1ll * ifac[i] * ifac[i] % mod;
    }

    int up = poly::pre(n + m);
    poly::ntt(f, up, 0), poly::ntt(g, up, 0);
    for (int i = 0; i != up; i++) {
        f[i] = 1ll * f[i] * g[i] % mod;
    }
    poly::ntt(f, up, 1);

    int ans = 1;
    for (int i = 0; i <= n + m; i++) {
        ans = (ans + 1ll * f[i] * fac[i] % mod * fac[i]) % mod;
    }

    memset(f, 0, sizeof f), memset(g, 0, sizeof g);
    for (int i = 1; i != n; i++) {
        f[i] = 1ll * ifac[i - 1] * ifac[i + 1] % mod;
    }
    for (int j = 1; j != m; j++) {
        g[j] = 1ll * ifac[j - 1] * ifac[j + 1] % mod;
    }
    poly::ntt(f, up, 0), poly::ntt(g, up, 0);
    for (int i = 0; i != up; i++) {
        f[i] = 1ll * f[i] * g[i] % mod;
    }
    poly::ntt(f, up, 1);
    for (int i = 0; i <= n + m; i++) {
        ans = (ans + 1ll * (mod - f[i]) * fac[i] % mod * fac[i]) % mod;
    }
    ans = 2 * ans % mod;

    ans = (ans + 1ll * (mod - c(n + m - 2, n - 1)) * c(n + m - 2, n - 1) + 1ll * c(n + m - 2, n - 2) * c(n + m - 2, n)) % mod;

    for (int l = 0; l < m - 2; l++) {
        int v = (1ll * c(l + n - 1, n - 1) * c(l + n - 1, n - 1) + 1ll * (mod - c(l + n - 1, n)) * c(l + n - 1, n - 2)) % mod;
        ans = (ans + 1ll * (m - 2 - l) * v) % mod;
    }
    for (int l = 0; l < n - 2; l++) {
        int v = (1ll * c(l + m - 1, m - 1) * c(l + m - 1, m - 1) + 1ll * (mod - c(l + m - 1, m)) * c(l + m - 1, m - 2)) % mod;
        ans = (ans + 1ll * (n - 2 - l) * v) % mod;
    }

    cout << ans << endl;
}