#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int INF = 1e9 + 10;
const ll INFL = 4e18;

#include <atcoder/modint>
#include <atcoder/fenwicktree>
using mint = atcoder::modint998244353;

int main() {
    int N, K;
    cin >> N >> K;

    atcoder::fenwick_tree<mint> fen(N + 1);
    mint ans = 0;

    fen.add(0, 1);
    for (int i = 0; i <= N; i++) {
        if (i - K >= 0) {
            mint res = fen.sum(0, i - K + 1);
            fen.add(i, res);
        }

        ans += fen.sum(i, i + 1);
    }

    cout << ans.val() << endl;
}