#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

int n;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n, k;
    cin >> n >> k;
    vector<vector<int>> u(n, vector<int> (n));
    vector<vector<int>> d(n, vector<int> (n));
    d[k - 1][k - 1] = 1;
    u[k - 1][k - 1] = 1;
    for(int i = k; i < n; ++i){
        u[k - 1][i] = 1;
        d[k - 1][i] = 1;
    }
    for(int i = k + 1; i < n; ++i){
        u[i][0] = 0;
        d[i][0] = u[i - 1][n - 1];
        for(int j = 1; j < n; ++j){
            if(i - j < k - 1){
                d[i][j] = d[i][j - 1];
                u[i][j] = u[i][j - 1];
            }
            else{
                u[i][j] = d[i - j - 1][j - 1] + u[i][j - 1];
                d[i][j] = d[i - j - 1][n - 1] - d[i - j - 1][j] + d[i][j - 1];
            }
        }

    }
    cout << d[n - 1][n - 1] + u[n - 1][n - 1] << "\n";


}