#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using mint = atcoder::modint998244353;

int main(){
    int n, k;
    cin >> n >> k;
    vector<mint> dp(n + 1);
    dp[0] = 1, dp[1] = -1;
    for(int i = 0; i < n; i++){
        dp[i + 1] += dp[i];
        if(i + k <= n) dp[i + k] += dp[i];
    }
    cout << accumulate(dp.begin(), dp.end(), mint(0)).val() << '\n';
}