#include <bits/stdc++.h>
using namespace std;
const int N = 5010;
int f[N];
int n, k;
int main() {
    cin >> n >> k;
    if (k == 1) {
        cout << 1 << endl;
        exit(0);
    }
    f[1] = 1;
    f[2] = 2;

    for (int i = 3; i <= n; i++)
        for (int j = max(i - k, 1); j <= max(1, i - 1); j++)
            f[i] += f[j];
    cout << f[n] << endl;
    return 0;
}