#include<iostream>
using namespace std;
int a[1000], n, m;
int main()
{
cin >> n >> m;
a[0] = 1;
for (int i = 1;i <= m;i++)
{
for (int j = 0;j < i;j++)
{
a[i] += a[j];
}
}
for (int i = m+1;i <= n;i++)
{
for (int j = i - m;j < i;j++)
{
a[i] += a[j];
}
}
cout << a[n] << endl;
return 0;
}