#include <atcoder/modint>
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using mint = atcoder::modint998244353;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

void solve() {
  ll n, k;
  cin >> n >> k;
  vector<mint> sum(n + 10, 0);
  sum[1] = 1;
  mint ans = 1;
  for (ll i = 1; i <= n; i++) {
    sum[i + 1] = sum[i];
    if (i < k)
      continue;
    sum[i + 1] += sum[i - k + 1];
    ans += sum[i + 1] - sum[i];
  }
  cout << ans.val() << '\n';
}

int main() {
  std::cin.tie(nullptr);
  std::ios_base::sync_with_stdio(false);
  int T = 1;
  for (int t = 0; t < T; t++) {
    solve();
  }
  return 0;
}