#include <bits/stdc++.h>

using namespace std;

using ll = long long;

const int mod = 998244353;

void add(int &x, int y) { if ((x += y - mod) < 0) x += mod; }
int quo2(int x) { return (x + (x & 1 ? mod : 0)) >> 1; }

const int N = 5e5;

int n, m;
int inv[N * 2 + 5];
int f[N + 5], fs[N + 5], g[N * 2 + 5], h[N * 2 + 5];
void solve(int n, int w) {
  h[0] = 1, h[1] = n * 2 + 1;
  for (int i = 2; i <= m * 2; ++i)
    h[i] = ((ll)(n * 2 + 1) * h[i - 1] + (ll)(i - 1) * h[i - 2]) % mod * inv[i] % mod;
  for (int i = 0; i <= m * 2; ++i) g[i] = (g[i] + (ll)h[i] * w) % mod;
}

int ans;

int main() {
  scanf("%d%d", &n, &m), ++m;
  inv[1] = 1;
  for (int i = 2; i <= m * 2; ++i) inv[i] = (ll)(mod - mod / i) * inv[mod % i] % mod;
  f[0] = 1;
  for (int i = 1; i <= m; ++i)
    f[i] = (ll)(i + quo2(mod - 3)) * f[i - 1] % mod * inv[i] % mod;
  fs[0] = 1;
  for (int i = 1; i <= m; ++i) add(fs[i] = f[i], fs[i - 1]);
  solve(n - 1, 1), solve(n, mod - 2), solve(n + 1, 1);
  for (int i = 0; i <= m; ++i)
    ans = (ans + (ll)g[i * 2] * f[i] % mod * fs[m - i]) % mod;
  if (ans = quo2(ans)) ans = mod - ans;
  printf("%d\n", ans);
}