bb.cc

// https://codeiq.jp/ace/kawazoe/q1339
#include <iostream>
#include <vector>
long long k_bonacci(const int &k, const int &n){
    std::vector<long long> v(k, 0);
    long long res = v.back() = 1;
    for(int i = 0; i < n; ++i) std::swap(v[i%k] = res * 2 - v[i%k], res);
    return res;
}
int main(){
    int n, k;
    std::cin >> n >> k;
    std::cout << k_bonacci(k+1, n) - k_bonacci(k, n) << std::endl;
    return 0;
}